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Sample records for superconducting composites cu-2

  1. Structure, magnetic and superconducting properties of MoSr2HoCu2O8-δ

    International Nuclear Information System (INIS)

    Balchev, N.; Nenkov, K.; Mihova, G.; Kunev, B.; Pirov, J.; Dimitrov, D.A.

    2009-01-01

    Samples with nominal composition MoSr 2 HoCu 2 O 8-δ were synthesized and their magnetic and superconducting (SC) properties were investigated. The obtained samples are Mo-deficient. It was established that the magnetic order is of a long-range type. The coincidence of the experimental value of the Curie constant and the theoretical one of MoSr 2 HoCu 2 O 8-δ shows that the observed magnetic properties of the samples are determined by the highly dominating phase Mo-1212. The two-step resistive SC transition, together with the absence of both diamagnetism and a peak in the specific heat between the two critical temperatures may be associated with the presence of a granular superconductivity. The effect of the Mo-deficiency on the magnetic and SC properties of MoSr 2 HoCu 2 O 8-δ was discussed

  2. Raman scattering spectra of superconducting Bi2Sr2CaCu2O8 single crystals

    International Nuclear Information System (INIS)

    Kirillov, D.; Bozovic, I.; Geballe, T.H.; Kapitulnik, A.; Mitzi, D.B.

    1988-01-01

    Raman spectra of Bi 2 Sr 2 CaCu 2 O 8 single crystals with superconducting phase-transition temperature of 90 K have been studied. The spectra contained phonon lines and electronic continuum. Phonon energies and polarization selection rules were measured. A gap in the electronic continuum spectrum was observed in a superconducting state. Noticeable similarity between Raman spectra of Bi 2 Sr 2 CaCu 2 O 8 and YBa 2 Cu 3 O 7 was found

  3. Raman scattering spectra of superconducting Bi2Sr2CaCu2O8 single crystals

    Science.gov (United States)

    Kirillov, D.; Bozovic, I.; Geballe, T. H.; Kapitulnik, A.; Mitzi, D. B.

    1988-12-01

    Raman spectra of Bi2Sr2CaCu2O8 single crystals with superconducting phase-transition temperature of 90 K have been studied. The spectra contained phonon lines and electronic continuum. Phonon energies and polarization selection rules were measured. A gap in the electronic continuum spectrum was observed in a superconducting state. Noticeable similarity between Raman spectra of Bi2Sr2CaCu2O8 and YBa2Cu3O7 was found.

  4. Reinforced fluropolymer nanocomposites with high-temperature superconducting Bi2Sr2CaCu2Oy

    Science.gov (United States)

    Jayasree, T. K.

    2014-10-01

    Bismuth Strontium Calcium Copper Oxide (Bi2Sr2CaCu2Oy)/Polyvinylidene fluoride (PVDF) nanocomposite was prepared and their thermal properties were analyzed. The composite consists of the polyvinylidene fluoride (PVDF) as an insulating polymer matrix, and homogenously distributed Bismuth strontium calcium copperoxide (2212) nanoparticles. SEM data shows flaky grains of the superconductor coated and linked by polymer. Differential scanning calorimetry (DSC) results indicated that the melting point was not affected significantly by the addition of BSCCO. However, the addition of superconducting ceramic resulted in an extra melting peak at a lower temperature (145°C). Thermogravimetric analysis of the samples shows that the onset decomposition temperature of the PVDF matrix was decreased by the addition of SC filler.

  5. Superconductivity at 108 K in the simplest non-toxic double-layer cuprate of Ba2CaCu2O4(O,F)2

    International Nuclear Information System (INIS)

    Shirage, P M; Shivagan, D D; Crisan, A; Tanaka, Y; Kodama, Y; Kito, H; Iyo, A

    2008-01-01

    We report the superconductivity in apical fluorine system of Ba 2 CaCu 2 O 6-y F y : the second member of Ba 2 Ca n-1 Cu n O 2n (O,F) 2 homologous series. The polycrystalline samples of Ba 2 CaCu 2 O 6-y F y (F-0212) were synthesized under high pressure as a parameter of nominal fluorine content (y). Samples with y = 2.0 ∼ 1.2 elucidating the very sharp superconducting transitions in temperature dependence of susceptibility from under doping state to slightly over doping state via optimal doping state. A remarkable highest T c of 108 K has been achieved for the sample synthesized from a nominal composition of Ba 2 CaCu 2 O 4.4 F 1.6 . This T c is highest among the double CuO 2 layered system except for that including toxic elements such as Hg and T1. The T c has been systematically controlled from 57 K to 108 K by controlling the doping state, by designing the starting composition of fluorine and oxygen. The strong dependence of the 'a' and 'c' lattice constants were found on the nominal F content. We propose the Ba 2 CaCu 2 O 4 (O,F) 2 as a promising material for practical use due to its high T c and non-toxicity with a simple crystal structure

  6. Effect of Cu2O morphology on photocatalytic hydrogen generation and chemical stability of TiO2/Cu2O composite.

    Science.gov (United States)

    Zhu, Lihong; Zhang, Junying; Chen, Ziyu; Liu, Kejia; Gao, Hong

    2013-07-01

    Improving photocatalytic activity and stability of TiO2/Cu2O composite is a challenge in generating hydrogen from water. In this paper, the TiO2 film/Cu2O microgrid composite was prepared via a microsphere lithography technique, which possesses a remarkable performance of producing H2 under UV-vis light irradiation, in comparison with pure TiO2 film, Cu2O film and TiO2 film/Cu2O film. More interesting is that in TiO2 film/Cu2O microgrid, photo-corrosion of Cu2O can be retarded. After deposition of Pt on its surface, the photocatalytic activity of TiO2/Cu2O microgrid in producing H2 is improved greatly.

  7. Effective charge separation in BiOI/Cu2O composites with enhanced photocatalytic activity

    Science.gov (United States)

    Xia, Yongmei; He, Zuming; Yang, Wei; Tang, Bin; Lu, Yalin; Hu, Kejun; Su, Jiangbin; Li, Xiaoping

    2018-02-01

    Novel BiOI/Cu2O composites were designed and synthesized for the first time by coupling reduction method at low temperature. The samples were characterized by XRD, XPS, SEM, EDS, HRTEM, UV-vis (DRS), FTIR and photo-electro-chemical (PEC) analysis. Results showed that the BiOI/Cu2O composites consisted of three-dimensional (3D), hierarchical cauliflower-like structure composed of BiOI nanosheet and Cu2O cubic submicrometer structure, the composite absorption band broadened, and the absorption intensity in the visible region strengthened. And the composites exhibited an excellent photocatalytic performance, which might be attributed to the improvement of the composite absorption and effective charge separation in BiOI/Cu2O composites. In addition, the possible photocatalytic mechanism was proposed.

  8. Controllable synthesis and enhanced photocatalytic properties of Cu2O/Cu31S16 composites

    International Nuclear Information System (INIS)

    Liu, Xueqin; Li, Zhen; Zhang, Qiang; Li, Fei

    2012-01-01

    Highlights: ► Facile sonochemical route. ► The content of Cu 31 S 16 in the Cu 2 O/Cu 31 S 16 can be easily controlled. ► Structure and optical properties of Cu 2 O/Cu 31 S 16 were discussed. ► Enhanced photocatalytic property of Cu 2 O/Cu 31 S 16 . ► Cu 2 O/Cu 31 S 16 core/shell structures were more stable than single Cu 2 O particles. -- Abstract: The controlled synthesis of Cu 2 O/Cu 31 S 16 microcomposites with hierarchical structures had been prepared via a convenient sonochemical route. Ultrasonic irradiation of a mixture of Cu 2 O and (NH 2 ) 2 CS in an aqueous medium yielded Cu 2 O/Cu 31 S 16 composites. The content of Cu 31 S 16 in the Cu 2 O/Cu 31 S 16 can be easily controlled by adjusting the synthesis time. The Cu 31 S 16 layer not only protected and stabilized Cu 2 O particles, but also prohibited the recombination of photogenerated electrons–holes pair between Cu 31 S 16 and Cu 2 O. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) spectra, ultraviolet–visible (UV–Vis) spectroscopy and photoluminescence (PL) spectroscopy were used to characterize the products. Photocatalytic performance of the Cu 2 O/Cu 31 S 16 hierarchical structures was evaluated by measuring the decomposition rate of methyl orange solution under natural light. To the best of our knowledge, this is the first report on the preparation and photocatalytic activity of Cu 2 O/Cu 31 S 16 microcomposite. Additionally, the Cu 2 O/Cu 31 S 16 core/shell structures were more stable than single Cu 2 O particles during photocatalytic process since the photocatalytic activity of the second reused architecture sample was much higher than that of pure Cu 2 O. The Cu 2 O/Cu 31 S 16 microcomposites may be a good promising candidate for wastewater treatment.

  9. Unusual behavior of nuclear relaxation in CeCu2Si2 'possible evidence for triplet superconductivity'

    International Nuclear Information System (INIS)

    Kitaoka, Y.; Asayama, K.; Ueda, K.; Kohara, T.

    1984-01-01

    Nuclear relaxation of 63 Cu in the superconducting state of the Kondo-lattice system CeCu 2 Si 2 has been studied with the use of the 63 Cu nuclear quadrupole resonance technique under zero field and down to 65mK. The nuclear spin-lattice relaxation rate (1/T 1 ) decreases drastically just below Tsub(c)=0.67 K down to 0.5Tsub(c) without the apparent enhanced behavior and then is found to be almost temperature independent below 0.3Tsub(c). These results suggest that the superconductivity in CeCu 2 Si 2 is not in the usual BCS regime. The analysis based upon the existing triplet pairing model with an anisotropic energy gap describes well the behavior from Tsub(c) down to 0.5Tsub(c), while the temperature independence below 0.3Tsub(c) remains unexplained. (author)

  10. High temperature superconductivity in Zn and Mn substituted (Tl,Cr)Sr2CaCu2O7

    International Nuclear Information System (INIS)

    Lo, S.V.; Abd Shukor, R.

    1999-01-01

    Samples with nominal starting composition (TICr 0 .15)Sr 2 (Ca 1-x M x )Cu 2 O 7 (TI-1212) for x=0 - 0.7 with M= Zn and Mn have been prepared and investigated by powder X-ray diffraction (XRD) and electrical resistance measurements. All sample showed a mixed phase of 1212 and 1201. Dominant 1212-phase was observed for x=0.0-0.5 and x=0.0-0.4, for Zn and Mn series, respectively. The superconducting transition temperature was suppressed when Zn and Mn are substituted at the Ca site. For the Zn series the normal state behavior is metallic throughout the doping range. For the Mn series the normal state behavior is metallic for 0.1≤x≥0.3 and semiconducting like x>0.3. The suppression of T c and formation of the TI-1212 phase are discussed in terms of the ionic radius and valence state of the substituted elements. (author)

  11. Enhanced Thermoelectric Properties of Graphene/Cu2SnSe3 Composites

    Directory of Open Access Journals (Sweden)

    Degang Zhao

    2017-02-01

    Full Text Available Cu2SnSe3 material is regarded as a potential thermoelectric material due to its relatively high carrier mobility and low thermal conductivity. In this study, graphene was introduced into the Cu2SnSe3 powder by ball milling, and the bulk graphene/Cu2SnSe3 thermoelectric composites were prepared by spark plasma sintering. The graphene nanosheets distributed uniformly in the Cu2SnSe3 matrix. Meanwhile, some graphene nanosheets tended to form thick aggregations, and the average length of these aggregations was about 3 μm. With the fraction of graphene increasing, the electrical conductivity of graphene/Cu2SnSe3 samples increased greatly while the Seebeck coefficient was decreased. The introduction of graphene nanosheets can reduce the thermal conductivity effectively resulting from the phonon scattering by the graphene interface. When the content of graphene exceeds a certain value, the thermal conductivity of graphene/Cu2SnSe3 composites starts to increase. The achieved highest figure of merit (ZT for 0.25 vol % graphene/Cu2SnSe3 composite was 0.44 at 700 K.

  12. Anomalous spectral weight transfer at the superconducting transition of Bi2Sr2CaCu2O8+δ

    International Nuclear Information System (INIS)

    Dessau, D.S.; Wells, B.O.; Shen, Z.; Spicer, W.E.; Arko, A.J.; List, R.S.; Mitzi, D.B.; Kapitulnik, A.

    1991-01-01

    Anomalous spectral weight transfer at the superconducting transition of single-crystalline Bi 2 Sr 2 CaCu 2 O 8+δ was observed by high-resolution angle-resolved photoemission spectroscopy. As the sample goes superconducting, not only is there spectral weight transfer from the gap region to the pileup peak as in BCS theory, but along the Γ-bar M direction there is also some spectral weight transfer from higher binding energies in the form of a dip. In addition, we note that at the superconducting transition there is a decrease (increase) in the occupied spectral weight for the spectra taken along Γ-bar M (Γ-X)

  13. Superconducting composites materials

    International Nuclear Information System (INIS)

    Kerjouan, P.; Boterel, F.; Lostec, J.; Bertot, J.P.; Haussonne, J.M.

    1991-01-01

    The new superconductor materials with a high critical current own a large importance as well in the electronic components or in the electrotechnical devices fields. The deposit of such materials with the thick films technology is to be more and more developed in the years to come. Therefore, we tried to realize such thick films screen printed on alumina, and composed mainly of the YBa 2 Cu 3 O 7-δ material. We first realized a composite material glass/YBa 2 Cu 3 O 7-δ , by analogy with the classical screen-printed inks where the glass ensures the bonding with the substrate. We thus realized different materials by using some different classes of glass. These materials owned a superconducting transition close to the one of the pure YBa 2 Cu 3 O 7-δ material. We made a slurry with the most significant composite materials and binders, and screen-printed them on an alumina substrate preliminary or not coated with a diffusion barrier layer. After firing, we studied the thick films adhesion, the alumina/glass/composite material interfaces, and their superconducting properties. 8 refs.; 14 figs.; 9 tabs [fr

  14. Superconductivity in Multiple Phase Sr2Ln1–xCaxGaCu2O7 and Characterization of La2–xSrxCaCu2O6+δ

    NARCIS (Netherlands)

    Cava, R.J.; Dover, R.B. van; Batlogg, B.; Krajewski, J.J.; Schneemeyer, L.F.; Siegrist, T.; Hessen, B.; Chen, H.; Peck, Jr.; Rupp, Jr. L.W.

    1991-01-01

    We have observed the occurrance of superconductivity at temperatures between 40 and 50K for multiple phase samples of Sr2Ln1–xCaxGaCu2O7 treated at 950-1000°C at 25 atmospheres oxygen pressure. We have not been able to find conditions at oxygen pressures of 25 atmospheres or below which make single

  15. Superconducting composite for magnetic bearings

    International Nuclear Information System (INIS)

    Rigney, T.K. II.

    1995-01-01

    A composite includes granules of Type II superconducting material and granules of rare-earth permanent magnets that are distributed in a binder. The composite is a two-phase structure that combines the properties of the superconductor and magnets with the flexibility and toughness of a polymeric material. A bearing made from this composite has the load capacity and stiffness of a permanent magnet bearing with added stability from a Type II superconducting material. 7 figs

  16. Synthesis and photocatalytic activity of carbon spheres loaded Cu2O/Cu composites

    International Nuclear Information System (INIS)

    Li, Yinhui; Zhao, Mengyao; Zhang, Na; Li, Ruijuan; Chen, Jianxin

    2015-01-01

    Highlights: • Carbon spheres loaded Cu 2 O/Cu composites are obtained by hydrothermal process. • Cu 2 O/Cu nanocrystals grow on the surface of carbon spheres. • The composites with core–shell structure show highly photo-catalytic activity. • The composites can degrade methyl orange under simulated solar light irradiation. • The composites can be used to treat dye wastewater or organic pollutants. - Abstract: In this work, using amylose as carbon source and cupric acetate as copper source, carbon spheres loaded Cu 2 O/Cu composites were obtained by hydrothermal synthesis. The effects of the molar ratios between glucose and Cu(II), and hydrothermal time on the morphology and sizes of the composites were investigated. The result of photocatalytic experiments demonstrated that the composites could degrade methyl orange in aqueous solution under simulated solar light irradiation. The highest degradation rate was achieved to 93.83% when the composites were prepared by hydrothermal synthesis at 180 °C for 16 h and the molar ratio between glucose and Cu(II) was 10/1. The composites, as new and promising materials, can be used to treat dye wastewater or other organic pollutants

  17. Inducing phase decomposition and superconductivity of Bi2Sr2CaCu2Oy single crystals treated in sulphur atmosphere at low temperature

    International Nuclear Information System (INIS)

    Chen, Q.W.; China Univ. of Science and Technology, Hefei, AH; Wu, W.B.; Qian, Y.T.; China Univ. of Science and Technology, Hefei, AH; Wang, L.B.; Li, F.Q.; Zhou, G.E.; Chen, Z.Y.; Zhang, Y.H.

    1995-01-01

    As it has been pointed out, phase decomposition which may be hard to be detected in a polycrystalline system and is likely to correlate with changes in both oxygen content and microstructure, has been observed frequently in annealed single crystals especially at higher temperatures (> 500 C). This is still an open question to some degree because the mechanism of phase decomposition is very complex and is dominated by the composition of the Bi-2212 phase, the condition of heat treatment, and the atmosphere. Hence, inducing oxygen loss at low temperature to avoid the evaporation of Bi atoms and other undetected structure changes which would occur at higher temperature annealing undoubtedly provides important information about the relationship between oxygen loss and phase decomposition, as well as the relationship between oxygen content and superconductivity. In this note, we report on the results of treatments of Bi 2 Sr 2 CaCu 2 O y single crystals in sulphur atmosphere at 160 C. (orig.)

  18. NMR studies of spin excitations in superconducting Bi2Sr2CaCu2O8+δ single crystals

    Science.gov (United States)

    Takigawa, M.; Mitzi, D. B.

    1994-08-01

    The oxygen NMR shift and the Cu nuclear spin-lattice relaxation rate (1/T1) were measured in Bi2.1Sr1.9Ca0.9Cu2.1O8+δ single crystals. While both the shift and 1/(T1T) decrease sharply near Tc, 1/(T1T) becomes nearly constant at low temperatures, indicating a gapless superconducting state with finite density of states at the Fermi level. From the oxygen shift data, the residual spin susceptibility at T=0 is estimated to be 10% of the value at room temperature. Our results are most consistent with a d-wave pairing model with strong (resonant) impurity scattering.

  19. Oxygen stoichiometry and its influence on superconductivity in Bi2Sr2CaCu2O8+x

    International Nuclear Information System (INIS)

    Krishnaraj, P.; Lelovic, M.; Eror, N.G.; Balachandran, U.

    1994-01-01

    Bi 2 Sr 2 CaCu 2 O 8+x (2212) was synthesized from freeze-dried precursors. The oxygen content of 2212 was determined as a function of temperature and oxygen partial pressure and the variation of Tc with oxygen content was determined. It was found that 2212 without excess oxygen (x = 0) is superconducting. This points to the role of the (Bi-O) ∞ layers as a source for holes in 2212. Four probe resistivity measurements were also performed on 2212. The nature of oxygen intercalation and oxygen removal in 2212 was studied by thermogravimetry and resistivity. It was also found that samples of 2212 with the same oxygen content had different T c 's depending on thermal history. This difference in T c is thought to arise from oxygen occupying different sites in the lattice while maintaining the same total oxygen content

  20. Current-carrying capacity dependence of composite Bi2Sr2CaCu2O8 superconductors on the liquid coolant conditions

    International Nuclear Information System (INIS)

    Romanovskii, V R; Watanabe, K; Awaji, S; Nishijima, G

    2006-01-01

    The thermal runaway conditions of the composite Bi 2 Sr 2 CaCu 2 O 8 superconductor cooled by liquid helium or liquid hydrogen are compared. The study based on the static analysis of thermoelectric modes was made when the volume fraction of the superconductor in a composite was varied. Some specific trends underlying the onset of thermal runaway in superconducting composites cooled by liquid coolants are discussed. It is stated that the operating modes of superconducting composites may be characterized by stable states during which the current-carrying capacity of a superconductor is not effectively used even with a high amount of superconductor in the composite. These states are possible due to the corresponding temperature variation of the resistivities of the matrix and the superconductor in the high operating temperature range. They have to be considered in experiments when the critical current of a superconductor is determined or when the optimal stable operating modes of the current-carrying elements based on the Bi 2 Sr 2 CaCu 2 O 8 superconductor, which is cooled by liquid coolant, are defined

  1. Superconducting glass-ceramics in BiSrCaCu2Al0.5Ox---Comparison between rod and powder compacted specimens

    International Nuclear Information System (INIS)

    Hirata, K.; Abe, Y.

    1991-01-01

    Superconducting properties are studied for glass-ceramics which were prepared by reheating glass rods and the glass powder compacts in the BiSrCaCu 2 Al 0.5 O x system, respectively. The glass-ceramic rod specimens obtained by reheating rod glass at 800--830 degree C for 50 h have a T c (R=0) of 85 K, while the disk specimens obtained by reheating the powered glass compacts in the same way do not exhibit superconductivity above 77 K. This difference in superconductivity between the specimens is discussed in terms of crystallization process and the amount of oxygen absorption of the specimens during heating

  2. Critical energy of superconducting composites

    International Nuclear Information System (INIS)

    Jayakumar, R.

    1987-01-01

    The stability of superconducting composites is studied in one-dimensional geometry and critical quench energies are calculated by solving for the steady state temperature profile which gives the minimum energy. The present calculations give lower values for the critical energy than previous estimates. The calculations are shown to be applicable to both direct cooled and impregnated conductors. Critical energies are also calculated including the effect of temperature dependence of conductor properties. (author)

  3. Composition superconductive plumbous coatings

    International Nuclear Information System (INIS)

    Volodin, V.N.; Tuleushev, A.Zh.; Tuleushev, Yu.Zh.; Lisizin, V.N.

    2002-01-01

    Independent dispersion of two or more targets, precipitation of pulverized material on substrate and possibility of composition change in wide range of component concentrations made possible ion-plasma forming of film composition materials from materials with different chemical and physical qualities, particularly in lead-aluminum, lead-beryllium and lead-graphite systems. Named systems are characterized in wide sphere of immiscibility in solid and liquid state and absence of intermediate compounds. It is impossible to receive materials from them in traditional method in conditions of gravitational field. In lead-aluminum system there was received a number of film coatings with aluminum content up to 95 at. % at coating thickness up to 2 μm. Owing to X-ray investigations it is fixed that lead and aluminum have been performed by separate phases. Lead in sprayed layer represents well-crystallized phase with grain size more than 100 nm; texturing is not found. Study of physical qualities has shown that materials with lead base 21.6 at. % Al) have enough high crystalline current in comparison with compact lead, which reaches (2.5-3.0)·10 5 A)·cm 2 , while materials with aluminum base (21.6 at. % Al) loose this effect and critical temperature of transition is reduced from 7.1 to 5.8 K. It was impossible to carry out X-rayed analysis for lead-beryllium film because of weak intensity of beryllium lines against a background of lead owing to a quite large difference of atomic balance. Cryogen tests have shown the increase of critical current strength up to (3.1-3.6)·10 4 A)·cm 2 or composition coating of lead-beryllium (56.99 at. % or 5,45 mas. % Be), at that the critical temperature of transition does not differ from lead temperature. Samples of lead edge of state diagram have been received in the lead-graphite system. X-ray investigation subjected coating contained 6.81 at. % (55.82 mas. %) of lead. Choice of the composition is conditioned on possibilities of

  4. Electrical transport effects due to oxygen content modifications in a Bi2Sr2CaCu2O8+δ superconducting whisker

    International Nuclear Information System (INIS)

    Cagliero, Stefano; Agostino, Angelo; Bonometti, Elisabetta; Truccato, Marco

    2007-01-01

    We report a set of resistivity measurements along the a-axis of a Bi 2 Sr 2 CaCu 2 O 8+δ microscopic superconducting whisker. The effect of the storage environment on sample ageing has been studied, considering both an air atmosphere at 273 K and a helium atmosphere at about 300 K for an overall storage time of about 100 days. It is clearly shown that the material underwent a remarkable resistivity increase of 26% at 260 K accompanied by a decrease in the critical temperature of 0.6 K during the whole ageing period. The helium atmosphere increased the average process rate by about two orders of magnitude. The present results are in agreement with previous findings on room temperature structural modifications in Bi 2 Sr 2 CaCu 2 O 8+δ whiskers and can be ascribed to oxygen depletion phenomena from the material

  5. Superconducting composites materials. Materiaux composites supraconducteurs

    Energy Technology Data Exchange (ETDEWEB)

    Kerjouan, P; Boterel, F; Lostec, J; Bertot, J P; Haussonne, J M [Centre National d' Etudes des Telecommunications (CNET), 22 - Lannion (FR)

    1991-11-01

    The new superconductor materials with a high critical current own a large importance as well in the electronic components or in the electrotechnical devices fields. The deposit of such materials with the thick films technology is to be more and more developed in the years to come. Therefore, we tried to realize such thick films screen printed on alumina, and composed mainly of the YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} material. We first realized a composite material glass/YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}, by analogy with the classical screen-printed inks where the glass ensures the bonding with the substrate. We thus realized different materials by using some different classes of glass. These materials owned a superconducting transition close to the one of the pure YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} material. We made a slurry with the most significant composite materials and binders, and screen-printed them on an alumina substrate preliminary or not coated with a diffusion barrier layer. After firing, we studied the thick films adhesion, the alumina/glass/composite material interfaces, and their superconducting properties. 8 refs.; 14 figs.; 9 tabs.

  6. Cu2O/CuO Bilayered Composite as a High-Efficiency Photocathode for Photoelectrochemical Hydrogen Evolution Reaction

    Science.gov (United States)

    Yang, Yang; Xu, Di; Wu, Qingyong; Diao, Peng

    2016-10-01

    Solar powered hydrogen evolution reaction (HER) is one of the key reactions in solar-to-chemical energy conversion. It is desirable to develop photocathodic materials that exhibit high activity toward photoelectrochemical (PEC) HER at more positive potentials because a higher potential means a lower overpotential for HER. In this work, the Cu2O/CuO bilayered composites were prepared by a facile method that involved an electrodeposition and a subsequent thermal oxidation. The resulting Cu2O/CuO bilayered composites exhibited a surprisingly high activity and good stability toward PEC HER, expecially at high potentials in alkaline solution. The photocurrent density for HER was 3.15 mA·cm-2 at the potential of 0.40 V vs. RHE, which was one of the two highest reported at the same potential on copper-oxide-based photocathode. The high photoactivity of the bilayered composite was ascribed to the following three advantages of the Cu2O/CuO heterojunction: (1) the broadened light absorption band that made more efficient use of solar energy, (2) the large space-charge-region potential that enabled a high efficiency for electron-hole separation, and (3) the high majority carrier density that ensured a faster charge transportation rate. This work reveals the potential of the Cu2O/CuO bilayered composite as a promising photocathodic material for solar water splitting.

  7. Limiting currents in superconducting composites

    International Nuclear Information System (INIS)

    Keilin, V.E.; Romanovskii, V.R.

    1992-01-01

    In this paper the results of numerical and analytical calculations of the process of current charging into a round superconducting composite with properties homogenized over cross-section are presented. In the numerical solution taken was into account a common proceeding of the thermal and electromagnetic processes. A wire with real volt-ampere characteristics approximated by exponential dependence was considered. The calculations carried out at various rates of current charging, voltampere characteristics, matrix materials, heat transfer coefficients and other parameters showed: the existence of characteristic limiting value of current below which the wire remains in a superconducting state if the current charging ceases and above which changes into a normal state; this current is somewhat less than a quench current; the existence of finite value for limiting current at any low heat transfer from a surface. The analytical solution of the problem is given. It permitted to write the stability criterion from which the dependence of limiting currents on initial parameters follows. The wire nonisothermality, its heat capacity, thermal and electric conductivities are taken into account additionally, as compared to results published earlier

  8. Synthesis and photocatalytic CO2 reduction performance of Cu2O/Coal-based carbon nanoparticle composites

    Science.gov (United States)

    Dedong, Zhang; Maimaiti, Halidan; Awati, Abuduheiremu; Yisilamu, Gunisakezi; Fengchang, Sun; Ming, Wei

    2018-05-01

    The photocatalytic reduction of CO2 into hydrocarbons provides a promising approach to overcome the challenges of environmental crisis and energy shortage. Here we fabricated a cuprous oxide (Cu2O) based composite photocatalyst consisting of Cu2O/carbon nanoparticles (CNPs). To prepare the CNPs, coal samples from Wucaiwan, Xinjiang, China, were first treated with HNO3, followed by hydrogen peroxide (H2O2) oxidation to strip nanocrystalline carbon from coal. After linking with oxygen-containing group such as hydroxyl, coal-based CNPs with sp2 carbon structure and multilayer graphene lattice structure were synthesized. Subsequently, the CNPs were loaded onto the surface of Cu2O nanoparticles prepared by in-situ reduction of copper chloride (CuCl2·2H2O). The physical properties and chemical structure of the Cu2O/CNPs as well as photocatalytic activity of CO2/H2O reduction into CH3OH were measured. The results demonstrate that the Cu2O/CNPs are composed of spherical particles with diameter of 50 nm and mesoporous structure, which are suitable for CO2 adsorption. Under illumination of visible light, electron-hole pairs are generated in Cu2O. Thanks to the CNPs, the fast recombination of electron-hole pairs is suppressed. The energy gradient formed on the surface of Cu2O/CNPs facilitates the efficient separation of electron-hole pairs for CO2 reduction and H2O oxidation, leading to enhanced photocatalytic activity.

  9. Interplay of superconductivity and bosonic coupling in the peak-dip-hump structure of Bi2Sr2CaCu2O8 +δ

    Science.gov (United States)

    Miller, Tristan L.; Zhang, Wentao; Ma, Jonathan; Eisaki, Hiroshi; Moore, Joel E.; Lanzara, Alessandra

    2018-04-01

    Because of the important role of electron-boson interactions in conventional superconductivity, it has long been asked whether any similar mechanism is at play in high-temperature cuprate superconductors. Evidence for strong electron-boson coupling is observed in cuprates with angle-resolved photoemission spectroscopy (ARPES), in the form of a dispersion kink and peak-dip-hump structure. What is missing is evidence of a causal relation to superconductivity. Here we revisit the problem using the technique of time-resolved ARPES on Bi2Sr2CaCu2O8 +δ . We focus on the peak-dip-hump structure, and show that laser pulses shift spectral weight into the dip as superconductivity is destroyed on picosecond time scales. We compare our results to simulations of Eliashberg theory in a superconductor with an Einstein boson, and find that the magnitude of the shift in spectral weight depends on the degree to which the bosonic mode contributes to superconductivity. Further study could address one of the longstanding mysteries of high-temperature superconductivity.

  10. Anelastic characterization and superconducting properties of RuSr2GdCu2O8+δ

    Directory of Open Access Journals (Sweden)

    Jurelo, A. R.

    2008-08-01

    Full Text Available Since the discovery of the high Tc superconductors, many researches have been carried out on the different properties of these materials, especially on the transition temperature into the superconducting state. The rutheno-cuprates belong to a new class of composites, which were synthesized for the first time by Bauernfeind in 1995. Bernhard and collaborators discovered, in 1999, the coexistence of the ferromagnetism and the superconductivity in this phase, which is known as antagonistic phenomenon in the electromagnetism due to spin-charge interactions established in these states. However, the physical nature of the superconducting and magnetic states is still very obscure. The non-stoichiometric (interstitial oxygen is considered as a possible cause for the non-uniformity of the sample properties. In this paper, results of mechanical spectroscopy in Ru-1212 samples are presented showing complex anelastic spectra, which were attributed to the mobility of the interstitial oxygen atoms in the Ru-1212 lattice.Desde el descubrimiento de los superconductores de alta Tc, muchas investigaciones han sido realizadas sobre las diferentes propiedades de estos materiales, especialmente sobre la temperatura de transición dentro del estado superconductor. Los cupratos de rutenio pertenecen a una nueva clase de compositos, los cuales fueron sintetizados por primera vez por Bauernfeind en 1995. Bernhard y colaboradores descubrieron, en 1999, la coexistencia del ferromagnetismo y la superconductividad en esta fase, lo cual es conocido como un fenómeno antagonistico en el electromagnetismo debido a las interacciones spin-carga establecidas en estos estados. Sin embargo, la naturaleza física de los estados superconductores y magnéticos aun no son muy claros. El oxigeno no-estequiométrico (intersticial es considerado como una causa de la no-uniformidad de las propiedades de la muestra. En este articulo, los resultados de espectroscopia mecánica en muestras

  11. Destruction of superconductivity in the Bi2Sr2Ca1-xGdxCu2-yLiyO8+d system

    International Nuclear Information System (INIS)

    Jayaram, B.; Lanchester, P.C.; Weller, M.T.

    1991-01-01

    We have measured the T c , resistivity, and magnetoresistivity of a series of Bi 2 Sr 2 Ca 1-x Gd x Cu 2-y Li y O 8+d samples, with x=0 and 0.4 and 0≤y≤0.6. We find that the suppression of T c , the logarithmic variation of the resistivity above the superconducting transition, and the field-independent nature of the temperature variation of magnetoresistivity illustrate the enhancement of the Coulomb interaction with increasing normal-state resistivity (ρ n ). We also find a gradual crossover from a logarithmic to an exponential dependence with increasing ρ n

  12. Microimpurity composition of superconducting ceramics

    International Nuclear Information System (INIS)

    Zhiglov, Yu.S.; Poltoratskij, Yu.B.; Protsenko, A.N.; Tuchin, O.V.

    1989-01-01

    Using laser mass spectrometry, the microimpurity composition of YBa 2 Cu 3 O 7-y superconducting ceramics, prepared by routine solid-phase synthesis from extremely pure yttrium and copper oxides and BaCO 3 , is determined. The presence of F, Na, Al, P, Cl, S, K, Ca impurities, which concentration in specimens varies within 10 -3 +5x10 -3 at.% and also Si, Sr, Fe of about 1x10 -1 at.% is established. It is difficult to determine concentrations of C, N, H 2 O impurities because of the presence of background signals of residual gases in the chamber. Using the method of Auger electron spectroscopy, a surface layer of HTSC ceramics grain is studied. The availability of chlorine impurity, which amount considerably exceeds its volume concentration, is determined in near the surface layer. 2 refs.; 2 figs

  13. On the relations among the pseudogap, electronic charge order and Fermi-arc superconductivity in Bi2Sr2CaCu2O8+δ

    International Nuclear Information System (INIS)

    Oda, M; Liu, Y H; Kurosawa, T; Takeyama, K; Ido, M; Momono, N

    2008-01-01

    On the basis of STM/STS, break-junction tunneling and electronic Raman scattering experiments on Bi 2 Sr 2 CaCu 2 O 8+δ reported so far, we suggest that the static, electronic charge order is associated with inhomogeneous electronic states on antinodal parts of the Fermi surface that are outside the Fermi-arc around the node and responsible for the pseudogap, and coexists with the homogeneous superconductivity caused by the pairing of coherent quasiparticles on the Fermi-arc, the so-called 'Fermi-arc superconductivity', in the real space, although the two electronic orders or the corresponding energy gaps compete with each other in the k-space

  14. Composite superconducting wires produced by rapid coating in Bi-Sr-Ca-Cu-O metal oxide system

    International Nuclear Information System (INIS)

    Grozav, A.D.; Konopko, L.A.; Leoporda, N.I.

    1989-01-01

    Method for producing superconducting composite wires by dip coating of copper wires in metal-oxide BiSrCaCu 2 O x melt is developed. The thickness of the coating is regulated by the change of dip rate, melt viscosity and by the number of passages through the melt. Wire annealing at 700-800 deg C leads to the production of two phases, one of them being superconducting with T c =80K

  15. Co-reduction self-assembly of reduced graphene oxide nanosheets coated Cu2O sub-microspheres core-shell composites as lithium ion battery anode materials

    International Nuclear Information System (INIS)

    Xu, Yi-Tao; Guo, Ying; Song, Le-Xin; Zhang, Kai; Yuen, Matthew M.F.; Xu, Jian-Bin; Fu, Xian-Zhu; Sun, Rong; Wong, Ching-Ping

    2015-01-01

    Cuprous oxide (Cu 2 O) sub-microspheres @ reduced graphene oxide (rGO) nanosheets core-shell composites with 3D architecture are successfully fabricated by a one-step method through co-reduction of irregular cupric citrate and graphene oxide nanosheets at room temperature. Comparing to the bare Cu 2 O sub-microspheres and the simple physical mixture of Cu 2 O and rGO (Cu 2 O-rGO-M), the Cu 2 O@rGO electrodes demonstrate dramatically improved capacity, cyclic stability and rate capability as anode materials for lithium ion batteries. At a low current density of 100 mA∙g −1 , Cu 2 O@rGO electrodes deliver a discharge capacity of 534 mAh∙g −1 after 50 cycles, retaining 94% of the initial capacity. Under a higher current density of 1000 mA∙g −1 , Cu 2 O@rGO electrodes exhibit a discharge capacity of 181 mAh∙g −1 after 200 cycles, approximately 4 times larger than that of bare Cu 2 O sub-microsphere electrodes. The rate capacity retention of Cu 2 O@rGO electrode is 74% at 200 mA∙g −1 and 38% at 1000 mA∙g −1 relative to 100 mA∙g −1 , much better than that for Cu 2 O-rGO-M (52% and 34%) and bare Cu 2 O electrodes (13% and 3%,). The enhanced electrochemical performance for Cu 2 O@rGO might be ascribed to the rGO coating and 3D architecture. The outer coated rGO nanosheets could provide additional 3D conductive networks as well as serve as the buffer layers for accommodating the large volume change of the inner Cu 2 O sub-microspheres during the charge-discharge cycling

  16. Composite conductor containing superconductive wires

    Energy Technology Data Exchange (ETDEWEB)

    Larson, W.L.; Wong, J.

    1974-03-26

    A superconductor cable substitute made by coworking multiple rods of superconductive niobium--titanium or niobium--zirconium alloy with a common copper matrix to extend the copper and rods to form a final elongated product which has superconductive wires distributed in a reduced cross-section copper conductor with a complete metallurgical bond between the normal-conductive copper and the superconductor wires contained therein is described. The superconductor cable can be in the form of a tube.

  17. Chemical reactivities of the superconducting oxides, YBa2Cu3Oy and BiSrCaCu2Oy

    International Nuclear Information System (INIS)

    Toyama, Hisashi; Mizuno, Noritaka; Misono, Makoto

    1989-01-01

    The chemical reactivities of YBa 2 Cu 3 O y and BiSrCaCu 2 O y with various gases have been studied. It was found that large quantities of NO, CO, and NO 2 were rapidly absorbed (or intercalated) in the bulk of YBa 2 Cu 3 O y (T c : 90 K) at 573 K. The amount absorbed was in the order NO ∼ CO ∼ NO 2 > O 2 ∼ CO 2 > N 2 O ∼ 0. The amount for NO was more than two times the amount of YBa 2 Cu 3 O y in molar ratio and elongation by about 0.2 angstrom along c-axis was observed. NO absorbed was almost completely recovered as NO by the evacuation at 773 K. This absorption-desorption cycle proceeded reversively. The electronic resistivity at 573 K of YBa 2 Cu 3 O y increased upon the NO absorption and was restored by the evacuation at 773 K. CO was also absorbed rapidly accompanied by evolution of CO 2 . BiSrCaCu 2 O y did not absorb either NO or CO

  18. Direct observation of interlayer Josephson vortices in heavily Pb-doped Bi2Sr2CaCu2Oy by scanning superconducting quantum interference device microscopy

    International Nuclear Information System (INIS)

    Kasai, Junpei; Hasegawa, Tetsuya; Okazaki, Noriaki; Koinuma, Hideomi; Nakayama, Yuri; Shimoyama, Jun-ichi; Kishio, Kohji; Motohashi, Teruki; Matsumoto, Yuji

    2006-01-01

    Josephson vortices trapped in cross-sectional edge surfaces of Pb 0.6 Bi 1.4 Sr 2 CaCu 2 O y has been directly observed by using a scanning superconducting quantum interference device (SQUID) microscope. The magnetic field distribution B z around each vortex is substantially anisotropic, compared with the usual vortex in the ab-plane, and is extended over 100 μm toward the in-plane direction. By fitting a theoretical B z function to experimental ones, c-axis penetration depth λ c was estimated to be 11.2 ±0.7 μm, which is in good agreement with the literature value, 12.6 μm, obtained from the Josephson plasma edge frequency. (author)

  19. Enhancement of the superconducting properties of TlBa2CaCu2O7+δ thin films via postannealing

    International Nuclear Information System (INIS)

    Siegal, M.P.; Venturini, E.L.; Newcomer, P.P.; Morosin, B.; Overmyer, D.L.; Dominguez, F.; Dunn, R.

    1995-01-01

    The superconducting properties of TlBa 2 CaCu 2 O 7+δ (Tl-1212) films are greatly enhanced by annealing in unreactive ambients such as nitrogen at temperatures ranging from T a =250--600 degree C. The transition temperature, T c , of these Tl-1212 films as-grown in oxygen is 70 K. Annealing for 1 h at 250 degree C elevates T c above 90 K. T c further increases and sharpens for T a =600 degree C. In addition, subtle changes occur in the microstructure correlating with improved critical current density. These results indicate that Tl-1212 films may be of greater relevance for electronics applications than previously believed. copyright 1995 American Institute of Physics

  20. Nuclear relaxation behavior of the superconducting cuprates: Bi2Sr2CaCu2O8

    Science.gov (United States)

    Walstedt, R. E.; Bell, R. F.; Mitzi, D. B.

    1991-10-01

    Nuclear-magnetic-resonance data are presented and analyzed for the high-Tc compound Bi2Sr2CaCu2O8 for two oxygen doping levels. Both sample conditions lead to spin-gap behavior for the NMR shift, with a precursive downturn in the data at T>Tc. In addition, the relaxation times T1 obey the relation (T1T)-1~Ks(T) at low temperatures (T<~100 K), where Ks(T) is the spin paramagnetic shift. This relation, which is also obeyed by other superconductors, is argued to be related to the spin-gap effects and thus incompatible with a Fermi-liquid approach to the understanding of these systems.

  1. Emergent loop-nodal s(±)-wave superconductivity in CeCu(2)Si(2): similarities to the iron-based superconductors.

    Science.gov (United States)

    Ikeda, Hiroaki; Suzuki, Michi-To; Arita, Ryotaro

    2015-04-10

    Heavy-fermion superconductors are prime candidates for novel electron-pairing states due to the spin-orbital coupled degrees of freedom and electron correlations. Superconductivity in CeCu_{2}Si_{2} discovered in 1979, which is a prototype of unconventional (non-BCS) superconductors in strongly correlated electron systems, still remains unsolved. Here we provide the first report of superconductivity based on the advanced first-principles theoretical approach. We find that the promising candidate is an s_{±}-wave state with loop-shaped nodes on the Fermi surface, different from the widely expected line-nodal d-wave state. The dominant pairing glue is magnetic but high-rank octupole fluctuations. This system shares the importance of multiorbital degrees of freedom with the iron-based superconductors. Our findings reveal not only the long-standing puzzle in this material, but also urge us to reconsider the pairing states and mechanisms in all heavy-fermion superconductors.

  2. Manufacturing of superconductive silver/ceramic composites

    DEFF Research Database (Denmark)

    Seifi, Behrouz; Bech, Jakob Ilsted; Eriksen, Morten

    2000-01-01

    Manufacturing of superconducting metal/ceramic composites is a rather new discipline within materials forming processes. High Temperature SuperConductors, HTSC, are manufactured applying the Oxide-Powder-In-Tube process, OPIT. A ceramic powder containing lead, calcium, bismuth, strontium, and cop......Manufacturing of superconducting metal/ceramic composites is a rather new discipline within materials forming processes. High Temperature SuperConductors, HTSC, are manufactured applying the Oxide-Powder-In-Tube process, OPIT. A ceramic powder containing lead, calcium, bismuth, strontium...

  3. Effect of oxygen content on the electrical transport and superconducting properties of Pb0.5Sr2.5Y0.6Ca0.4Cu2O7-y

    International Nuclear Information System (INIS)

    Ruan, K.Q.; China Univ. of Science and Technology, Hefei, AH; Jin, H.; China Univ. of Science and Technology, Hefei, AH; Feng, Y.; China Univ. of Science and Technology, Hefei, AH; Zhou, Y.Q.; China Univ. of Science and Technology, Hefei, AH; Chui, X.D.; China Univ. of Science and Technology, Hefei, AH; Wang, C.Y.; China Univ. of Science and Technology, Hefei, AH; Cao, L.Z.; China Univ. of Science and Technology, Hefei, AH; Wang, L.B.; Zhang, Y.H.

    1997-01-01

    Two kinds of methods have been used to synthesize Pb 0.5 Sr 2.5 Y 0.6 Ca 0.4 Cu 2 O 7-y samples. The synthesized sample using the first method shows superconductivity, while that using the second method exhibits a localized behavior at low temperatures Thermogravimetric analysis (TGA) and electrical transport measurements have been carried out on superconducting and nonsuperconducting samples grown under the two kinds of synthesis conditions and the effect of oxygen content on the transport and superconducting properties is discussed briefly. (orig.)

  4. Oxygen vacancy rich Cu2O based composite material with nitrogen doped carbon as matrix for photocatalytic H2 production and organic pollutant removal.

    Science.gov (United States)

    Lu, Lele; Xu, Xinxin; Yan, Jiaming; Shi, Fa-Nian; Huo, Yuqiu

    2018-02-06

    A nitrogen doped carbon matrix supported Cu 2 O composite material (Cu/Cu2O@NC) was fabricated successfully with a coordination polymer as precursor through calcination. In this composite material, Cu 2 O particles with a size of about 6-10 nm were dispersed evenly in the nitrogen doped carbon matrix. After calcination, some coordinated nitrogen atoms were doped in the lattice of Cu 2 O and replace oxygen atoms, thus generating a large number of oxygen vacancies. In Cu/Cu2O@NC, the existence of oxygen vacancies has been confirmed by electron spin resonance (ESR) and X-ray photoelectron spectroscopy (XPS). Under visible light irradiation, Cu/Cu2O@NC exhibits excellent H 2 production with the rate of 379.6 μmol h -1 g -1 . Its photocatalytic activity affects organic dyes, such as Rhodamine B (RhB) and methyl orange (MO). In addition to photocatalysis, Cu/Cu2O@NC also exhibits striking catalytic activity in reductive conversion of 4-nitrophenol to 4-aminophenol with in presence of sodium borohydride (NaBH 4 ). The conversion efficiency reaches almost 100% in 250 s with the quantity of Cu/Cu2O@NC as low as 5 mg. The outstanding H 2 production and organic pollutants removal are attributed to the oxygen vacancy. We expect that Cu/Cu2O@NC will find its way as a new resource for hydrogen energy as well as a promising material in water purification.

  5. Removal of Cu 2+ Ions from Aqueous Medium Using Clinoptilolite/Emeraldine Base Composite

    Directory of Open Access Journals (Sweden)

    Silviya I. Lavrova

    2016-12-01

    Full Text Available The aim of this study was to investigate the removal efficiency of in situ synthesized composites consisted of emeraldine base and clinoptilolite on copper ions removal from aqueous medium. Two composite materials (Composite I and Composite II with different quantity of clinoptilolite were synthesised. The influence of the composite dosage, the contact time and the initial copper ions concentration has been studied. The results show that the significant removal of the copper ions becomes at the first minute of the contact between the composite material and the aqueous medium and the longer contact time leads to increasing of the copper ions removal. The removal efficiency at the 1st minute was 57.5% and 77.3% using Composite Iand Composite II, respectively. Maximum removal efficiency of 87.3% and 96.8% was achieved at the same dosage of Composite I and Composite II, respectively, at contact time of 360 minutes and temperature of 24 °C.

  6. Superconductivity proximate to antiferromagnetism in a copper-oxide monolayer grown on Bi2Sr2CaCu2O8 +δ

    Science.gov (United States)

    Wang, Shuai; Zhang, Long; Wang, Fa

    2018-01-01

    A nodeless superconducting (SC) gap was reported in a recent scanning tunneling spectroscopy experiment of a copper-oxide monolayer grown on a Bi2Sr2CaCu2O8 +δ (Bi2212) substrate [Zhong et al., Sci. Bull. 61, 1239 (2016), 10.1007/s11434-016-1145-4], which is in stark contrast to the nodal d -wave pairing gap in the bulk cuprates. Motivated by this experiment, we first show with first-principles calculations that the tetragonal CuO (T-CuO) monolayer on the Bi2212 substrate is more stable than the commonly postulated CuO2 structure. The T-CuO monolayer is composed of two CuO2 layers sharing the same O atoms. The band structure is obtained by first-principles calculations, and its strong electron correlation is treated with the renormalized mean-field theory. We argue that one CuO2 sublattice is hole doped while the other sublattice remains half filled and may have antiferromagnetic (AF) order. The doped Cu sublattice can show d -wave SC; however, its proximity to the AF Cu sublattice induces a spin-dependent hopping, which splits the Fermi surface and may lead to a full SC gap. Therefore, the nodeless SC gap observed in the experiment could be accounted for by the d -wave SC proximity to an AF order, thus it is extrinsic rather than intrinsic to the CuO2 layers.

  7. Strain tolerance of Bi2Sr2Ca1Cu2O8-δ/Ag composites at high field

    International Nuclear Information System (INIS)

    Li, Q.; Ostenson, J.E.; Finnemore, D.K.

    1991-01-01

    Strain tolerance of Bi 2 Sr 2 Ca 1 Cu 2 O 8-δ /Ag composites have been studied at fields up to 20 T and bending strains up to 2.6% in order to determine the factors that control the critical current density. The goal is to find the best way to distribute Ag such as to give both high strain tolerance and high critical current density. Partial melt processed samples prepared from micromilled mixtures containing 30% Ag by volume show a gradually decreasing critical current all the way out to 2.6% strain. Samples typically show about 1000 A/cm 2 at 4.2 K, 20 T, and 0.75% strain. At 20 K, these values occur at 4 T and 0.75% strain

  8. Thermal cycling in multifilamentary superconducting composites

    International Nuclear Information System (INIS)

    Aragao, E.E.A. de.

    1984-01-01

    NbTi-Cu multifilamentary superconducting composites were embedded, polished, characterized by microscopic techniques, and analyzed in a qualitative and semiquantitative way by energy dispersion technique. The superconductors were submitted to thermal cycling between the ambient temperature and the boiling point of helium (4.2K), for different number of cycles. The aims were to study the correlation between the possible microstructural damages due to thermal stresses arising in the composite during cycling and the variation of properties of the material with the number of cycles as well as to verify the validity of an elastic model for thermal stresses for low temperature cycles. (author)

  9. High-Q Tl2CaBa2Cu2O8 high-Tc superconducting quasi-optical millimeter-wave bandpass filters working at 77 K

    International Nuclear Information System (INIS)

    Zhang, D.; Fetterman, H.R.

    1994-01-01

    Tl 2 CaBa 2 Cu 2 O 8 high-temperature superconducting thin films with T c 's of over 100 K on LaAlO 3 substrates were used to fabricate quasi-optical millimeter-wave bandpass filters. Q-factors of over 400 were achieved, at liquid nitrogen temperatures from these filters at W-band frequencies (75--110 GHz)

  10. Charge Aspects of Composite Pair Superconductivity

    Science.gov (United States)

    Flint, Rebecca

    2014-03-01

    Conventional Cooper pairs form from well-defined electronic quasiparticles, making the internal structure of the pair irrelevant. However, in the 115 family of superconductors, the heavy electrons are forming as they pair and the internal pair structure becomes as important as the pairing mechanism. Conventional spin fluctuation mediated pairing cannot capture the direct transition from incoherent local moments to heavy fermion superconductivity, but the formation of composite pairs favored by the two channel Kondo effect can. These composite pairs are local d-wave pairs formed by two conduction electrons in orthogonal Kondo channels screening the same local moment. Composite pairing shares the same symmetries as magnetically mediated pairing, however, only composite pairing necessarily involves a redistribution of charge within the unit cell originating from the internal pair structure, both as a monopole (valence change) and a quadrupole effect. This redistribution will onset sharply at the superconducting transition temperature. A smoking gun test for composite pairing is therefore a sharp signature at Tc - for example, a cusp in the Mossbauer isomer shift in NpPd5Al2 or in the NQR shift in (Ce,Pu)CoIn5.

  11. Method of preparing composite superconducting wire

    International Nuclear Information System (INIS)

    Verhoeven, J. D.; Finnemore, D. K.; Gibson, E. D.; Ostenson, J. E.; Schmidt, F. A.

    1985-01-01

    An improved method of preparing composite multifilament superconducting wire of Nb 3 Sn in a copper matrix which eliminates the necessity of coating the drawn wire with tin. A generalized cylindrical billet of an alloy of copper containing at least 15 weight percent niobium, present in the copper as discrete, randomly distributed and oriented dendritic-shaped particles, is provided with at least one longitudinal opening which is filled with tin to form a composite drawing rod. The drawing rod is then drawn to form a ductile composite multifilament wire containing a filament of tin. The ductile wire containing the tin can then be wound into magnet coils or other devices before heating to diffuse the tin through the wire to react with the niobium forming Nb 3 Sn. Also described is an improved method for making large billets of the copper-niobium alloy by consumable-arc casting

  12. Fabrication of Cu2O-TiO2 Nano-composite with High Photocatalytic Performance under Simulated Solar Light

    Directory of Open Access Journals (Sweden)

    Yi Wentao

    2016-01-01

    Full Text Available Cu2O-P25 (TiO2 nano-heterostructures with different mass ratios were synthesized via a wet chemical precipitation and hydrothermal method, and were characterized by X-ray diffraction (XRD, field-emission scanning electron microscopy (FESEM, UV-vis diffuse reflectance spectra (DRS, and X-ray photoelectron spectroscopy (XPS. DRS results showed that the light absorption of P25 extended to the visible light region with the loading of Cu2O. XPS results showed that Cu existed in the state of Cu+ in the presence of hydroxylamine hydrochloride, confirming the formation of Cu2O. The obtained products exhibited efficient photocatalytic performance in degradation of methyl orange (MO and methylene blue (MB under simulated solar light. The sample of 5% Cu2O-P25 exhibited the highest photocatalytic activity among all as-prepared samples. And the photocatalysts can be recycled without obvious loss of photocatalytic activity.

  13. Microstructure, Mechanical and Tribological Properties of Ag/Bi2Sr2CaCu2O x Self-lubricating Composites

    Science.gov (United States)

    Tang, Hua; Zhang, Du; Wang, Yuqi; Zhang, Yi; Ji, Xiaorui; Song, Haojie; Li, Changsheng

    2014-01-01

    Ag/Bi2Sr2CaCu2O x self-lubricating composites were successfully fabricated by a facile powder metallurgy method. The structure and morphology of the as-synthesized composites and the worn surface after tribometer testing are characterized by using X-ray diffraction and scanning electron microscopy together with energy dispersive spectrometry. The results indicated that self-lubricating composites are composed of superconductor phase and Ag phase. Moreover, the effects of Ag on mechanical and tribological properties of the novel composites were investigated. The friction test results showed that the friction coefficient of the pure Bi2212 against stainless steel is about 0.40 at ambient temperature and abruptly decreases to about 0.17 when the temperature is cooled to 77 K. The friction coefficients of the composites from room temperature to high temperature were lower and more stable than those of pure Bi2Sr2CaCu2O x . When the content of Ag is 10 wt.%, the Ag/Bi2Sr2CaCu2O x composites exhibited excellent tribological performance, the improved tribological properties are attributed to the formation of soft metallic Ag films at the contacted zone of the composites.

  14. Superconductivity at 2.8 K and 1.5 kbar in κ-(BEDT-TTF)2Cu2(CN)3: The first organic superconductor containing a polymeric copper cyanide anion

    International Nuclear Information System (INIS)

    Geiser, Urs; Wang Hau, H.; Carlson, K.D.; Williams, J.M.; Charlier, H.A. Jr.; Heindl, J.E.; Yaconi, G.A.; Love, B.J.; Lathrop, M.W.; Schirber, J.E.; Overmyer, D.L.; Ren, Jingquing; Whangbo, Myung-Hwan

    1991-01-01

    Attempts to synthesize new k-phase superconductors have concentrated on ET salts with complex anions composed of Cu(I) or Ag(I) metal ions and pseudohalide anions. The 'targeted anion approach', by use of a preformed anion found in KCu 2 (CN) 3 .H 2 O and the presence of trace amounts of water, led to the discovery of the first copper-cyanide containing superconductor, K-(ET) 2 Cu 2 (CN) 3 . The crystal structure, superconducting properties, and band electronic structure are described in this article. The complex k-(ET) 2 Cu 2 (CN) 3 is in many ways similar to the superconductor K-(ET) 2 Cu[N(CN) 2 ]Cl, the superconductor with the highest T c reported to date. 28 refs., 3 figs

  15. Thermo-Exfoliated Graphite Containing CuO/Cu2(OH3NO3:(Co2+/Fe3+ Composites: Preparation, Characterization and Catalytic Performance in CO Conversion

    Directory of Open Access Journals (Sweden)

    Vladyslav V. Lisnyak

    2010-01-01

    Full Text Available Thermo-exfoliated graphite (TEG/CuO/Cu2(OH3NO3:(Co2+/Fe3+ composites were prepared using a wet impregnation method and subsequent thermal treatment. The physicochemical characterization of the composites was carried out by powder X-ray diffraction (PXRD, scanning electron microscopy (SEM and Ar temperature-desorption techniques. The catalytic efficiency toward CO conversion to CO2 was examined under atmospheric pressure. Characterization of species adsorbed over the composites taken after the activity tests were performed by means of temperature programmed desorption massspectrometry (TPD MS. (TEG/CuO/Cu2(OH3NO3:(Co2+/Fe3+ composites show superior performance results if lower temperatures and extra treatment with H2SO4 or HNO3 are used at the preparation stages. The catalytic properties enhancements can be related to the Cu2(OH3NO3 phase providing reaction centers for the CO conversion. It has been found that prevalence of low-temperature states of desorbed CO2 over high-temperature ones in the TPD MS spectra is characteristic of the most active composite catalysts.

  16. Fine filament NbTi superconductive composite

    International Nuclear Information System (INIS)

    Hong, S.; Grabinsky, G.; Marancik, W.; Pattanayak, D.

    1986-01-01

    The large superconducting magnet for the high energy physics accelerator requires fine filament composite to minimize the field error due to the persistent current in the filaments. New concepts toward the fine filament composite and its cable fabrication are discussed. Two-stage cables of fine wire with intermediate number of filaments were introduced. The first stage was six wires cables around one and in the second stage this was used to produce a Rutherford cable. The advantage of this process is in the ease of billet fabrication since the number of filaments in a single wire is within the range of easy billet fabrication. The disadvantage is in the cable fabrication. One of the major concerns in the fabrication of fine NbTi filaments composite in a copper matrix is the intermetallic compound formation during the extrusion and heat treatment steps. The hard intermetallic particles degrade the uniformity of the filaments and reduce the critical current density. The process of using Nb barrier between the filaments and copper matrix in order to prevent this CuTi intermetallic particle formation is described

  17. Radiation resistant organic composites for superconducting fusion magnets

    International Nuclear Information System (INIS)

    Nishijima, S.; Okada, T.

    1993-01-01

    Organic composite materials (usually reinforced by glas fibers: GFRP) are to be used in fusion superconducting magnets as insulating and/or structural materials. The fusion superconducting magnets are operated under radiation environments and hence the radiation induced degradation of magnet components is ought to be estimated. Among the components the organic composite materials were evaluated to be the most radiation sensitive. Consequently the development of radiation resistant organic composite materials is thought one of the 'key' technologies for fusion superconducting magnets. The mechanism of radiation-induced degradation was studied and the degradation of interlaminar shear strength (ILSS) was found to be the intrinsic phenomenon which controlled the overall degradation of organic composite materials. The degradation of ILSS was studied changing matrix resin, reinforcement and type of fabrics. The possible combination of the organic composites for the fusion superconducting magnet will be discussed. (orig.)

  18. Sorption properties of the activated carbon-zeolite composite prepared from coal fly ash for Ni(2+), Cu(2+), Cd(2+) and Pb(2+).

    Science.gov (United States)

    Jha, Vinay Kumar; Matsuda, Motohide; Miyake, Michihiro

    2008-12-15

    Composite materials of activated carbon and zeolite have been prepared successfully by activating coal fly ash (CFA) by fusion with NaOH at 750 degrees C in N(2) followed by hydrothermal treatments under various conditions. Uptake experiments for Ni(2+), Cu(2+), Cd(2+) and Pb(2+) were performed with the materials thus obtained from CFA. Of the various composite materials, that were obtained by hydrothermal treatment with NaOH solution (ca. 4M) at 80 degrees C (a composite of activated carbon and zeolite X/faujasite) proved to be the most suitable for the uptake of toxic metal ions. The relative selectivity of the present sorbents for the various ions was Pb(2+)>Cu(2+)>Cd(2+)>Ni(2+), with equilibrium uptake capacities of 2.65, 1.72, 1.44 and 1.20mmol/g, respectively. The sorption isotherm was a good fit to the Langmuir isotherm and the sorption is thought to progress mainly by ion exchange with Na(+). The overall reaction is pseudo-second order with rate constants of 0.14, 0.17, 0.21 and 0.20Lg/mmol min for the uptake of Pb(2+), Cu(2+), Cd(2+) and Ni(2+), respectively.

  19. Superconducting Tl2Ba2CaCu2O8 thin films prepared by post-annealing in a flow-through multiple-zone furnace

    International Nuclear Information System (INIS)

    Pluym, T.C.; Muenchausen, R.E.; Arendt, P.N.

    1994-01-01

    Tl 2 Ba 2 CaCu 2 O 8 thin films were prepared for the first time by use of a multiple-zone flow-through thallination process. Thallous oxide was volatilized from condensed thallium oxide in a low temperature source zone and convectively transported to a higher temperature thallination zone in which initially amorphous Ba 2 CaCu 2 O 5 precursor films were located. By careful control of the source temperature, film temperature, flow rate, anneal time, and rates of heat up and cool down, smooth Tl 2 Ba 2 CaCu 2 O 8 thin films were prepared on (100) LaAlO 3 with the following properties: inductive T c of 107.6 K and 80% transition width of 1.3 K, transport J c at 75 K of 1.3 x 10 5 A/cm 2 , and R s at 10 GHz and 80 K of 1.3 mΩ. The scalability of the process to large area film processing was demonstrated by the preparation of Tl 2 Ba 2 CaCu 2 O 8 thin films on LaAlO 3 three-inch diameter wafers

  20. Nano-fabricated superconducting radio-frequency composites, method for producing nano-fabricated superconducting rf composites

    Science.gov (United States)

    Norem, James H.; Pellin, Michael J.

    2013-06-11

    Superconducting rf is limited by a wide range of failure mechanisms inherent in the typical manufacture methods. This invention provides a method for fabricating superconducting rf structures comprising coating the structures with single atomic-layer thick films of alternating chemical composition. Also provided is a cavity defining the invented laminate structure.

  1. Phosphonic acids aid composition adjustment in the synthesis of Cu_2_+_xZn_1_−_xSnSe_4_−_y nanoparticles

    International Nuclear Information System (INIS)

    Ibáñez, Maria; Berestok, Taisiia; Dobrozhan, Oleksandr; LaLonde, Aaron; Izquierdo-Roca, Victor; Shavel, Alexey; Pérez-Rodríguez, Alejandro; Snyder, G. Jeffrey; Cabot, Andreu

    2016-01-01

    The functional properties of quaternary I_2–II–IV–VI_4 nanomaterials, with potential interest in various technological fields, are highly sensitive to compositional variations, which is a challenging parameter to adjust. Here we demonstrate the presence of phosphonic acids to aid controlling the reactivity of the II element monomer to be incorporated in quaternary Cu_2ZnSnSe_4 nanoparticles and thus to provide a more reliable way to adjust the final nanoparticle metal ratios. Furthermore, we demonstrate the composition control in such multivalence nanoparticles to allow modifying charge carrier concentrations in nanomaterials produced from the assembly of these building blocks.

  2. The influence of the precursor compositional ratio on Cu2ZnSnS4 films prepared by using sulfurization of the metallic precursor

    Science.gov (United States)

    Amal, Muhamad I.; Kim, Kyoo Ho

    2013-12-01

    Cu2ZnSnS4 (CZTS) films were prepared by using the sulfurization of sputtered metallic precursors. The compositional ratio of the CZTS films was slightly different compared to their initial metallic precursors due to elemental loss during annealing. The Cu/(Zn+Sn) ratio for the CZTS-1, CZTS-2 and CZTS-3 films were 0.91, 1.06 and 1.21, respectively. In addition, all films had a compositional ratio of Zn/Sn >1. The grain sizes of the CZTS films increased with increasing Cu ratio. X-ray diffraction and Raman spectroscopy showed that the CZTS films with an excess of copper and zinc had secondary phases of Cu2SnS3 and ZnS. The optical band gap and absorption coefficient for all CZTS films in the range of the experimental compositions were calculated to be 1.5 eV and >104 cm-1, respectively. The presence of secondary phases related to compositional ratio in the CZTS films influenced the electrical properties. The CZTS-1 film with a Cu-poor and Zn-rich composition whose a carrier concentration, an electrical mobility, and a resistivity values were 2.29 × 1018 cm-3, 10.29 cm2 V-1 s-1, 3.16 Ω cm, is the most suitable for solar-cell applications.

  3. Hydrostatic pressure dependence of the superconducting transition temperature of HgBa2CaCu2O6+δ and HgBa2Ca2Cu3O8+δ

    International Nuclear Information System (INIS)

    Klehe, A.K.; Schilling, J.S.

    1994-02-01

    The dependence of the superconducting transition temperature T c (P) on purely hydrostatic pressure to 0.9 GPa has been determined in ac susceptibility studies in a He-gas pressure system for optimally doped ceramic samples of HgBa 2 CaCu 2 O 6+δ and HgBa 2 Ca 2 Cu 3 O 8+δ with superconducting transitions at T c (0) ≅ 126.6 K and 133.9 K, respectively. T c increases reversibly under hydrostatic pressure at the rates, d T c /dP ≅ +1.80 ± 0.06 K/GPa and +1.71 ± 0.05 K/GPa, respectively. Within experimental error, these values are the same as found previously for optimally doped single-layered HgBa 2 CuO 4+δ , where d T c /dP ≅ +1.72 ± 0.05 K/GPa. Remarkably, the logarithmic volume derivative of T c is nearly identical for all three compounds, dln T c /dlnV ≅ -1.20 ± 0.05, even though the bulk modulus differs by more than 30%. This provides strong evidence that a common mechanism is responsible for the pressure dependence of the superconducting state in all three compounds

  4. Superconducting critical state of Bi2Sr2CaCu2O8: two-dimensional effects at low temperatures

    International Nuclear Information System (INIS)

    Rodriguez, E.; Goffman, M.F.; Arribere, A.; Cruz, F. de la; Schneemeyer, L.F.

    1994-01-01

    The critical current in the c direction of Bi 2 Sr 2 CaCu 2 O 8 is shown to increase with temperature in low temperature ZFC measurements. The results are consistent with a loss of the c direction long range phase correlation, induced by the temperature dependent critical current flowing in the ab planes. As a result of this and the loss of the long range correlation induced by thermal disorder, the low temperature electrical resistance of the ZFC critical state is finite at low temperatures, becomes zero and is finite again at higher temperature. (orig.)

  5. Raman scattering quantitative analysis of the anion chemical composition in kesterite Cu2ZnSn(SxSe1−x)4 solid solutions

    International Nuclear Information System (INIS)

    Dimitrievska, Mirjana; Gurieva, Galina; Xie, Haibing; Carrete, Alex; Cabot, Andreu; Saucedo, Edgardo; 2UB, Departament d’Electrònica, Universitat de Barcelona, C. Martí i Franquès 1, 08028 Barcelona (Spain))" data-affiliation=" (Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1 2pl., 08930 Sant Adrià del Besòs, Barcelona (Spain); IN2UB, Departament d’Electrònica, Universitat de Barcelona, C. Martí i Franquès 1, 08028 Barcelona (Spain))" >Pérez-Rodríguez, Alejandro

    2015-01-01

    Highlights: • An optical method for the quantitative measurement of [S]/([S] + [Se]) in CZTSSe is presented. • It is based on Raman spectroscopy and covers whole S–Se range of compositions. • The proposed method is independent of crystal quality, experimental conditions and type of material. • The validity of the technique is proven by comparison with independent composition measurements (XRD and EQE). • Test of the method on the data published in the literature has given satisfactory results. - Abstract: A simple and non destructive optical methodology for the quantitative measurement of [S]/([S] + [Se]) anion composition in kesterite Cu 2 ZnSn(S x Se 1−x ) 4 (CZTSSe) solid solutions by means of Raman spectroscopy in the whole S–Se range of compositions has been developed. This methodology is based on the dependence of the integral intensity ratio of Raman bands sensitive to anion vibrations with the [S]/([S] + [Se]) composition of the kesterite solid solutions. The calibration of the parameters used in this analysis involved the synthesis of a set of CZTSSe powders by solid state reaction method, spanning the range from pure Cu 2 ZnSnS 4 to pure Cu 2 ZnSnSe 4 . The validity of the methodology has been tested on different sets of independent samples, including also non-stoichiometric device grade CZTSSe layers with different compositions and films that were synthesized by solution based processes with different crystalline quality. In all cases, the comparison of the results obtained from the analysis of the intensity of the Raman bands with independent composition measurements performed by different techniques as X-ray diffraction and external quantum efficiency has confirmed the satisfactory performance of the developed methodology for the quantitative analysis of these compounds, independently on the crystal quality or the method of synthesis. Further strong support on the methodology performance has been obtained from the analysis of a wider

  6. Spectral investigation of hot-spot and cavity resonance effects on the terahertz radiation emitted from high-Tc superconducting Bi2Sr2CaCu2O8+δ single crystal mesa structures

    Science.gov (United States)

    Kadowaki, Kazuo; Watanabe, Chiharu; Minami, Hidetoshi; Yamamoto, Takashi; Kashiwagi, Takanari; Klemm, Richard

    2014-03-01

    Terahertz (THz) electromagnetic radiation emitted from high-Tc superconducting Bi2Sr2CaCu2O8+δ mesa structures in the case of single mesa and series-connected mesas is investigated by the FTIR spectroscopic technique while observing its temperature distribution simultaneously by a SiC photoluminescence technique. Changing the bias level, sudden jumps of the hot-spot position were clearly observed. Although the radiation intensity changes drastically associated with the jump of the hot spot position, the frequency is unaffected as long as the voltage per junction is kept constant. Since the frequency of the intense radiation satisfies the cavity resonance condition, we confirmed that the cavity resonance is of primarily importance for the synchronization of whole intrinsic Josephson junctions in the mesa for high power radiation. This work was supported in part by the Grant-in-Aid for challenging Exploratory Research, the Ministry of Education, Culture, Sports, Science & Technology (MEXT).

  7. Composite elements with superconducting ceramic materials and preparation process

    International Nuclear Information System (INIS)

    Drifford, M.; Lambard, J.

    1990-01-01

    Supraconducting ceramic powder is introduced in a ductile metal with an open porosity, then the tube is sealed at both ends and necked to form a composite element which is sintered and the ceramic becomes superconductive by gaseous diffusion. Then the composite element can be placed into a gasproof cladding [fr

  8. Growth of superconducting Bi2Sr2CaCu2O8+δ films by sedimentation deposition and liquid phase sintering and annealing technique

    International Nuclear Information System (INIS)

    Manahan, R.L.C.; Sarmago, R.V.

    2006-01-01

    We report on a technique of growing highly c-axis oriented Bi 2 Sr 2 CaCu 2 O 8+δ (Bi-2212) thick films on MgO substrate using a combined sedimentation-deposition and liquid phase sintering and annealing process. The temperature profiles employed partial melting followed by rapid cooling to temperature below the melting point. Scanning electron micrographs show that the films have a smooth surface. No evidence of grain boundaries on the film's surface can be seen. The critical temperatures of the samples range from ∼67 K to ∼81 K. This method presents a quick and easy preparation for high quality epitaxial Bi-2212 films

  9. Unusual Dispersion and Line Shape of the Superconducting State Spectra of Bi2Sr2CaCu2O8+δ

    International Nuclear Information System (INIS)

    Norman, M.R.; Ding, H.; Campuzano, J.C.; Takeuchi, T.; Ding, H.; Campuzano, J.C.; Takeuchi, T.; Randeria, M.; Yokoya, T.; Takahashi, T.; Mochiku, T.; Kadowaki, K.; Kadowaki, K.

    1997-01-01

    Photoemission spectra of Bi 2 Sr 2 CaCu 2 O 8+δ below T c show two features near the (π,0) point of the zone: a sharp peak at low energy and a higher binding energy hump. We find that the sharp peak persists at low energy even as one moves towards (0,0), while the broad hump shows significant dispersion which correlates well with the normal state dispersion. We argue that these features are naturally explained by the interaction of electrons with a sharp mode which appears only below T c , and speculate that the latter may be related to the resonance seen in recent neutron data. copyright 1997 The American Physical Society

  10. High-Field Quasiparticle Tunneling in Bi2Sr2CaCu2O8+δ : Negative Magnetoresistance in the Superconducting State

    International Nuclear Information System (INIS)

    Morozov, N.; Krusin-Elbaum, L.; Shibauchi, T.; Bulaevskii, L. N.; Maley, M. P.; Latyshev, Yu. I.; Yamashita, T.

    2000-01-01

    We report on the c -axis resistivity ρ c (H) in Bi 2 Sr 2 CaCu 2 O 8+δ that peaks in quasistatic magnetic fields up to 60 T. By suppressing the Josephson part of the two-channel (Cooper pair/quasiparticle) conductivity σ c (H) , we find that the negative slope of ρ c (H) above the peak is due to quasiparticle tunneling conductivity σ q (H) across the CuO 2 layers below H c2 . At high fields (a) σ q (H) grows linearly with H , and (b) ρ c (T) tends to saturate (σ c ≠0 ) as T→0 , consistent with the scattering at the nodes of the d -wave gap. A superlinear σ q (H) marks the normal state above T c . (c) 2000 The American Physical Society

  11. Study of vortex dynamics with local magnetic relaxation measurements in the superconducting compound Bi2Sr2CaCu2O8

    International Nuclear Information System (INIS)

    Berry, St.

    2000-01-01

    This experimental study of the magnetic field-temperature phase diagram and of the vortex dynamics in high- T c superconductors focuses on Bismuth-based cuprates: Bi 2 Sr 2 CaCu 2 O 8 . In type-II superconductors, mixed state characterized by the presence of vortices (quanta of magnetic flux) is divided by a transition line determined by two features of magnetization loops. For T > 40 K, magnetization loops vs applied field show a step evidence of a first order transition. From 20 to 40 K, a second peak replacing the step correspond to an abrupt increase of irreversibility interpreted as a bulk current. We want to understand the nature of the second peak (thermodynamic or nonequilibrium property) and separate phenomena contributing to irreversibility (flux pinning, geometrical or surface effects). Magnetic measurement techniques are nondestructive and have a resolution of few microns. Bi 2 Sr 2 CaCu 2 O 8 single crystals are optimized by localizing defectives regions with a magneto-optic technique for flux imaging and elimination of these regions with a wire saw. Local magnetization loops and relaxation measurements performed with a microscopic Hall probe array allow to distinguish irreversibility sources. The shape of induction profiles indicates which current dominate between surface current and bulk pinning induced current. Two crossover with time and a direct observation of two phases coexistence in induction profiles enlighten phenomena in play. The measured electric field-current density characteristics lead to barrier energy U(j) controlling thermally activated flux motion. Three relations (U(j) (surface, bulk low and high field) explain second peak. (author)

  12. Investigation of inter-grain critical current density in Bi2Sr2CaCu2O8+δ superconducting wires and its relationship with the heat treatment protocol

    Science.gov (United States)

    Pallecchi, I.; Leveratto, A.; Braccini, V.; Zunino, V.; Malagoli, A.

    2017-09-01

    In this work we investigate the effect of each different heat treatment stage in the fabrication of Bi2Sr2CaCu2O8+δ superconducting wires on intra-grain and inter-grain superconducting properties. We measure magnetic critical temperature T c values and transport critical current density J c at temperatures from 4 K to 40 K and in fields up to 7 T. From an analysis of the temperature dependence of the self-field critical current density J c(T) that takes into account weak link behavior and the proximity effect, we study grain boundary (GB) transparency to supercurrents; we also establish a relationship between GB oxygenation in the different steps of the fabrication process and GB transparency to supercurrents. We find that GB oxygenation starts in the first crystallization stage, but it becomes complete in the plateau at 836 °C and in slow cooling stages and is further enhanced in the prolonged post-annealing step. Such oxygenation makes GBs more conductive, thus improving the inter-grain J c value and temperature dependence. On the other hand, from inspection of the T c values in the framework of the phase diagram dome, we find that grains are already oxygenated in the crystallization step up to the optimal doping, while successive slow cooling and post-annealing treatments further enhance the degree of overdoping, especially if carried out in oxygen atmosphere rather than in air.

  13. LT-STM/STS observation of definite superconducting gap states on the multistage crystal surface of Bi2Sr2CaCu2O8+x

    International Nuclear Information System (INIS)

    Murakami, Hironaru; Aoki, Ryozo

    1996-01-01

    Low temperature STM/STS observations have been carried out on cleaved BSCCO crystal surfaces. The authors have succeeded in detection of a special layer, probably a CuO 2 or Ca layer exposed on the surface. The STS spectrum which was reproducibly observed on this special site shows a considerably anisotropic but distinct superconducting gap structure with a definite and flat gap bottom region. This gap structure shows significantly different characteristic from another gap structure observed on the BiO layer, which shows a rounded shape at the gap bottom region without any indication of a finite gap state

  14. Cooperative effects in CeCu2Si2

    International Nuclear Information System (INIS)

    Lang, M.; Modler, R.; Ahlheim, U.; Helfrich, R.; Reinders, P.H.P.; Steglich, F.; Assmus, W.; Sun, W.; Bruls, G.; Weber, D.; Luethi, B.

    1991-01-01

    Heavy-fermion superconductivity and other cooperative effects have been explored by thermal expansion, specific heat and ultrasound measurements on CeCu 2 Si 2 single crystals. Crystals annealed under Cu atmosphere show sharp superconducting transitions at Tc max =0.63 K. At the same temperature the ''as grown'', i.e., non-bulk-superconducting, crystals reveal a pronounced phase-transition anomaly, presumably of structural origin. This new transition is associated with an expansion of the volume upon cooling and gives rise to magnetic correlations. Our results indicate a complex interplay between lattice instability, magnetic phenomena and superconductivity in CeCu 2 Si 2 . (orig.)

  15. Filament bundle location influence on coupling losses in superconducting composites

    International Nuclear Information System (INIS)

    Ito, Daisuke; Koizumi, Misao; Hamajima, Takataro; Nakane, Fumoto.

    1983-01-01

    The ac losses in multifilamentary superconducting composites with different superconducting filament bundle positions have been measured using the magnetization method in order to reveal the relation between filament bundle position and coupling losses. Loss components depending on dB/dt in a mixed matrix superconducting composite, whose filament bundle is located in a central region surrounded by an outer stabilizing copper sheath, has been compared with another superconducting composite whose stabilizing copper is located in a central region surrounded by an outer filament bundle. In both conductors, key parameters, such as filament twistpitch, wire diameter and amount of copper stabilizer, were almost the same. Applied magnetic field is 2 Tesla with 0.05-2 Tesla/sec field change rate. Experimental results indicate that coupling losses between filaments in the composite with the filament bundle located in the central region is smaller than the composite with the filament bundle located in the outer region. A similar conclusion was reached theoretically by B. Truck. Coupling loss values obtained by the experiment show good agreement with calculated values with the equations proposed by B. Truck. It is also pointed out that a copper stabilizer, divided by the CuNi barrier into small regions, like a honeycomb, causes anomalous increasing in the copper resistivity due to Ni diffusion during heat treatment. (author)

  16. Preferred Orientation Contribution to the Anisotropic Normal State Resistivity in Superconducting Melt-Cast Processed Bi2Sr2CaCu2O8+δ

    Directory of Open Access Journals (Sweden)

    Aline Dellicour

    2017-05-01

    Full Text Available We describe how the contribution of crystallographic texture to the anisotropy of the resistivity of polycrystalline samples can be estimated by averaging over crystallographic orientations through a geometric mean approach. The calculation takes into account the orientation distribution refined from neutron diffraction data and literature values for the single crystal resistivity tensor. The example discussed here is a melt-cast processed Bi2Sr2CaCu2O8+δ (Bi-2212 polycrystalline tube in which the main texture component is a <010> fiber texture with relatively low texture strength. Experimentally-measured resistivities along the longitudinal, radial, and tangential directions of the Bi-2212 tube were compared to calculated values and found to be of the same order of magnitude. Calculations for this example and additional simulations for various texture strengths and single crystal resistivity anisotropies confirm that in the case of highly anisotropic phases such as Bi-2212, even low texture strengths have a significant effect on the anisotropy of the resistivity in polycrystalline samples.

  17. Superhydrophobic ceramic coatings enabled by phase-separated nanostructured composite TiO2–Cu2O thin films

    International Nuclear Information System (INIS)

    Aytug, Tolga; Paranthaman, Parans M; Simpson, John T; Christen, David K; Bogorin, Daniela F; Mathis, John E

    2014-01-01

    By exploiting phase-separation in oxide materials, we present a simple and potentially low-cost approach to create exceptional superhydrophobicity in thin-film based coatings. By selecting the TiO 2 –Cu 2 O system and depositing through magnetron sputtering onto single crystal and metal templates, we demonstrate growth of nanostructured, chemically phase-segregated composite films. These coatings, after appropriate chemical surface modification, demonstrate a robust, non-wetting Cassie–Baxter state and yield an exceptional superhydrophobic performance, with water droplet contact angles reaching to ∼172° and sliding angles <1°. As an added benefit, despite the photo-active nature of TiO 2 , the chemically coated composite film surfaces display UV stability and retain superhydrophobic attributes even after exposure to UV (275 nm) radiation for an extended period of time. The present approach could benefit a variety of outdoor applications of superhydrophobic coatings, especially for those where exposure to extreme atmospheric conditions is required. (papers)

  18. Superconductivity

    International Nuclear Information System (INIS)

    Taylor, A.W.B.; Noakes, G.R.

    1981-01-01

    This book is an elementray introduction into superconductivity. The topics are the superconducting state, the magnetic properties of superconductors, type I superconductors, type II superconductors and a chapter on the superconductivity theory. (WL)

  19. (Pt1-xCux)3Cu2B and Pt9Cu3B5, the first examples of copper platinum borides. Observation of superconductivity in a novel boron filled β-Mn-type compound

    Science.gov (United States)

    Salamakha, Leonid P.; Sologub, Oksana; Stöger, Berthold; Michor, Herwig; Bauer, Ernst; Rogl, Peter F.

    2015-09-01

    New ternary copper platinum borides have been synthesized by arc melting of pure elements followed by annealing at 600 °C. The structures have been studied by X-ray single crystal and powder diffraction. (Pt1-xCux)3Cu2B (x=0.33) forms a B-filled β-Mn-type structure (space group P4132; a=0.6671(1) nm). Cu atoms are distributed preferentially on the 8c atom sites, whereas the 12d site is randomly occupied by Pt and Cu atoms (0.670(4) Pt±0.330(4) Cu). Boron is located in octahedral voids of the parent β-Mn-type structure. Pt9Cu3B5 (space group P-62m; a=0.9048(3) nm, c=0.2908(1) nm) adopts the Pt9Zn3B5-δ-type structure. It has a columnar architecture along the short translation vector exhibiting three kinds of [Pt6] trigonal prism columns (boron filled, boron semi-filled and empty) and Pt channels with a pentagonal cross section filled with Cu atoms. The striking structural feature is a [Pt6] cluster in form of an empty trigonal prism at the origin of the unit cell, which is surrounded by coupled [BPt6] and [Pt6] trigonal prisms, rotated perpendicularly to the central one. There is no B-B contact as well as Cu-B contact in the structure. The relationships of Pt9Cu3B5 structure with the structure of Ti1+xOs2-xRuB2 as well as with the structure families of metal sulfides and aluminides have been elucidated. (Pt1-xCux)3Cu2B (x=0.3) (B-filled β-Mn-type structure) is a bulk superconductor with a transition temperature of about 2.06 K and an upper critical field μ0HC2(0)WHH of 1.2 T, whereas no superconducting transition has been observed up to 0.3 K in Pt9Cu3B5 (Pt9Zn3B5-δ-type structure) from electrical resistivity measurements.

  20. Contributions to the study of superconducting multifilamentary composites and cables

    International Nuclear Information System (INIS)

    Turck, B.

    1992-03-01

    This report is a collection of published papers in French and in English on superconducting composites and cables. All domains concerning the behaviour of superconductors in coils for field generation have been covered: critical current, current distribution, instabilities, losses in varying field. This document provides with expressions and criteria for conductor design, with conditions for achieving given performances and with criteria for design and optimization of structures of multifilamentary composites and cables. These publications have played a determining role in the understanding of the behaviour of superconductors and in their use in high performing magnets

  1. Melt processing of the Bi2Sr2CaCu2Oy superconductor in oxygen and argon atmospheres

    International Nuclear Information System (INIS)

    Holesinger, T.G.; Miller, D.J.; Chumbley, L.S.

    1992-08-01

    Solidification and subsequent annealing of Bi 2 Sr 2 CaCu 2 O y (2212) in oxygen and argon atmospheres were investigated in order to identify alternative processing routes for controlling microstructures and superconducting properties. In addition to 2212, several other phases formed on cooling in O 2 and did not disappear upon subsequent annealing. Crystallization in Ar resulted in a divorced eutetic structure of Bi 2 Sr 3-x Ca x O y and Cu 2 O/CuO. The superconductor was formed on subsequent anneals. Samples melted in Ar and then annealed generally possessed a more uniform microstructure compared with samples that were melted in oxygen and annealed. Compositional measurements of the 2212 phase suggest that CaO segregation in the melt may be minimized with an overall composition such as Bi 2.15 Sr 2 Ca 0.85 Cu 2 O y

  2. Fabrication and characterizations of high-Tc superconducting ceramic/polymer 0--3 composites

    International Nuclear Information System (INIS)

    Du, J.; Unsworth, J.

    1994-01-01

    High-T c superconducting ceramic YBa 2 Cu 3 O 7-x /thermosetting plastic 0--3 composites were fabricated. The structure, physical property, magnetic susceptibility, levitation, and mechanical strength of the composites were accessed. The influence of filler content on these properties was also studied. Although the 0--3 composites lack an electrical superconducting path through materials, the intrinsic diamagnetic properties were preserved. The magnetic superconducting transition temperature was not degraded. The values of magnetic susceptibility and levitation force for the composites were basically proportional to the actual volume fraction of superconducting filler. These new composite materials are most suitable for the applications in levitating vehicles and mechanical bearings

  3. Synthesis and characterizations of Cu2ZnSnS4 nanoparticles/carbon nanotube composite as an efficient absorber material for solar cell application

    Science.gov (United States)

    Das, S.; Sa, K.; Alam, I.; Mahakul, P. C.; Raiguru, J.; Subramanyam, B. V. R. S.; Mahanandia, P.

    2018-05-01

    In this energy crisis era, the urgent calls for clean energy converter realizes the importance of photovoltaic device, which offers the highest probability of delivering a sustainable way of harvesting solar energy. The active absorber layer has its significance towards the performance of photovoltaic device by absorbing solar light and creating electron-hole pair inside layer. Being a direct p-type semiconductor, Cu2ZnSnS4 generally referred as CZTS has emerged as potential absorber towards photovoltaics application in recent decades as it offers the advantage of tunable band gap near optimal region ˜1.45-1.65 eV favorably match the solar spectrum and a high absorption coefficient ˜104 cm-1. The further improvement in the performance of CZTS based photovoltaics has involved the use of carbon nanotubes (CNTs). Semiconductors hybridized with carbonaceous materials (CNTs) have been the center of attraction in the scientific community with beneficial contribution in enhancing optoelectronic properties. The incorporation of CNTs shows effectiveness in charge carrier transfer pathways which ultimately could enhance the photo conversion efficiency (PCE) of photovoltaic device cell (PVC). Here, a facile hydrothermal one-pot synthesis of CZTS nanoparticles and MWCNTs composite towards photovoltaics application is reported. The phase and structural analysis of CZTS nanoparticles as well as CZTS/MWCNTs composite is done by XRD. From FERSEM and TEM (LRTEM & HRTEM) analysis the CZTS nanoparticles decorated over the surface of MWCNTs is confirmed. The optical band gap of CZTS/MWCNTs composite is estimated to be 1.62 eV from UV-Visible spectra.

  4. Applications and fabrication processes of superconducting composite materials

    International Nuclear Information System (INIS)

    Gregory, E.

    1984-01-01

    This paper discusses the most recent applications and manufacturing considerations in the field of superconductivity. The constantly changing requirements of a growing number of users encourage development in fabrication and inspection techniques. For the first time, superconductors are being used commercially in large numbers and superconducting magnets are no longer just laboratory size. Although current demand for these conductors represents relatively small quantities of material, advances in the production of high-quality composites may accelerate technological growth into several new markets. Three large-scale application areas for superconductors are discussed: accelerator magnets for high-energy physics research, magnetic confinement for thermonuclear fusion, and magnetic resonance imaging for health care. Each application described is accompanied by a brief description of the conductors used and fabrication processes employed to make them

  5. Influence of growth conditions and weak fields on the electrical properties of the vortex and superconducting states of Bi2Sr2CaCu2O x thick tapes

    International Nuclear Information System (INIS)

    Naser, I.A.; Saleh, A.M.; Abu-Samreh, M.M.

    2005-01-01

    A systematic investigation of the electrical parameters of Bi 2 Sr 2 CaCu 2 O x thick tapes in the vortex and superconducting states was carried out. The tapes were grown on either single crystals of MgO or silver foil under different heat treatment conditions. The temperature dependence of the electrical resistivity in the vortex state was found to follow an Arrhenius-like relation of the form ρ(T, H) = ρ 0 exp(-U 0 (H)/k B T). The activation energy, U 0 , showed a strong dependence on the applied field and the growth conditions of the sample. Its average values were between 10 and 300 meV. The current-voltage characteristics (I-V) for various samples of different growth conditions and applied fields were also investigated. The study revealed a current dependence on the applied voltage was found to fit a power law of the form: I ∼ V α , where α is an exponent whose values are strongly dependent on growth conditions. At constant voltages, the current was found to decrease exponentially with the applied magnetic field according to I(B) ∼ exp(-cB/B *), where c is a constant depending on growth conditions and B * is a characteristic field of the sample. This exponential decay of the current is attributed to strong flux pinning centers. The dependence of the current on field and voltage could be written as I ∼ V α exp(-cB/B *). Furthermore, the heat treatment conditions and annealing atmosphere had strong influence on the I-V characteristic of the sample

  6. Superconductivity

    CERN Document Server

    Poole, Charles P; Farach, Horacio A

    1995-01-01

    Superconductivity covers the nature of the phenomenon of superconductivity. The book discusses the fundamental principles of superconductivity; the essential features of the superconducting state-the phenomena of zero resistance and perfect diamagnetism; and the properties of the various classes of superconductors, including the organics, the buckministerfullerenes, and the precursors to the cuprates. The text also describes superconductivity from the viewpoint of thermodynamics and provides expressions for the free energy; the Ginzburg-Landau and BCS theories; and the structures of the high

  7. Superconductivity

    International Nuclear Information System (INIS)

    Langone, J.

    1989-01-01

    This book explains the theoretical background of superconductivity. Includes discussion of electricity, material fabrication, maglev trains, the superconducting supercollider, and Japanese-US competition. The authors reports the latest discoveries

  8. Superconductivity

    International Nuclear Information System (INIS)

    Onnes, H.K.

    1988-01-01

    The author traces the development of superconductivity from 1911 to 1986. Some of the areas he explores are the Meissner Effect, theoretical developments, experimental developments, engineering achievements, research in superconducting magnets, and research in superconducting electronics. The article also mentions applications shown to be technically feasible, but not yet commercialized. High-temperature superconductivity may provide enough leverage to bring these applications to the marketplace

  9. A-15 superconducting composite wires and a method for making

    International Nuclear Information System (INIS)

    Suenaga, M.; Klamut, C. J.; Luhman, Th. S.

    1984-01-01

    A method for fabricating superconducting wires wherein a billet of copper containing filaments of niobium or vanadium is rolled to form a strip which is wrapped about a tin-alloy core to form a composite. The alloy is a tin-copper alloy for niobium filaments and a gallium-copper alloy for vanadium filaments. The composite is then drawn down to a desired wire size and heat treated. During the heat treatment process, The tin in the bronze reacts with the niobium to form the superconductor niobium tin. In the case where vanadium is used, the gallium in the gallium bronze reacts with the vanadium to form the superconductor vanadium gallium. This new process eliminates the costly annealing steps, external tin plating and drilling of bronze ingots required in a number of prior art processes

  10. Cyclic stress effects on transport properties of superconducting composite materials

    International Nuclear Information System (INIS)

    Fisher, E.S.; Kim, S.H.; Turner, A.P.L.

    1976-01-01

    The effects of cyclic stresses at 4.2 0 K on the conductor materials for large superconducting magnets are being investigted in samples of unalloyed copper and of composites containing Nb--Ti or Nb 3 Sn wires in a copper matrix. The samples are constant-strain cycled in pure tension-compression modes. The increase in electrical resistivity of different grades of copper with number and amplitude of cycles is described. The increases can be of the order of the magnetoresistance for 1000 to 2000 cycles at 0.20 percent strain per cycle. The facility for measuring critical current changes with composite cycling is described and the initial results indicate significant I/sub c/ changes as well as unexpected filament fractures. 10 fig

  11. Cell percolation model for electrical conduction of granular superconducting composites. 2

    International Nuclear Information System (INIS)

    Horvath, G.; Bankuti, J.

    1990-01-01

    The percolation of the electrical conductivity of the uniform cells is studied in an in-situ elongated granular superconducting composite on the basis of the uniform cell model improved previously. The critical temperatures are determined in the macroscopic superconducting state of the two- and the three-dimensional composites. (author)

  12. Superconductivity

    International Nuclear Information System (INIS)

    Andersen, N.H.; Mortensen, K.

    1988-12-01

    This report contains lecture notes of the basic lectures presented at the 1st Topsoee Summer School on Superconductivity held at Risoe National Laboratory, June 20-24, 1988. The following lecture notes are included: L.M. Falicov: 'Superconductivity: Phenomenology', A. Bohr and O. Ulfbeck: 'Quantal structure of superconductivity. Gauge angle', G. Aeppli: 'Muons, neutrons and superconductivity', N.F. Pedersen: 'The Josephson junction', C. Michel: 'Physicochemistry of high-T c superconductors', C. Laverick and J.K. Hulm: 'Manufacturing and application of superconducting wires', J. Clarke: 'SQUID concepts and systems'. (orig.) With 10 tabs., 128 figs., 219 refs

  13. Superconductivity

    International Nuclear Information System (INIS)

    Palmieri, V.

    1990-01-01

    This paper reports on superconductivity the absence of electrical resistance has always fascinated the mind of researchers with a promise of applications unachievable by conventional technologies. Since its discovery superconductivity has been posing many questions and challenges to solid state physics, quantum mechanics, chemistry and material science. Simulations arrived to superconductivity from particle physics, astrophysic, electronics, electrical engineering and so on. In seventy-five years the original promises of superconductivity were going to become reality: a microscopical theory gave to superconductivity the cloth of the science and the level of technological advances was getting higher and higher. High field superconducting magnets became commercially available, superconducting electronic devices were invented, high field accelerating gradients were obtained in superconductive cavities and superconducting particle detectors were under study. Other improvements came in a quiet progression when a tornado brought a revolution in the field: new materials had been discovered and superconductivity, from being a phenomenon relegated to the liquid Helium temperatures, became achievable over the liquid Nitrogen temperature. All the physics and the technological implications under superconductivity have to be considered ab initio

  14. Superconductivity

    CERN Document Server

    Thomas, D B

    1974-01-01

    A short general review is presented of the progress made in applied superconductivity as a result of work performed in connection with the high-energy physics program in Europe. The phenomenon of superconductivity and properties of superconductors of Types I and II are outlined. The main body of the paper deals with the development of niobium-titanium superconducting magnets and of radio-frequency superconducting cavities and accelerating structures. Examples of applications in and for high-energy physics experiments are given, including the large superconducting magnet for the Big European Bubble Chamber, prototype synchrotron magnets for the Super Proton Synchrotron, superconducting d.c. beam line magnets, and superconducting RF cavities for use in various laboratories. (0 refs).

  15. Phase transition study in a [Cu2 HgI4:0⋅xAgI] mixed composite system

    Indian Academy of Sciences (India)

    Administrator

    Diffraction, thermal analysis of compound, Ag2HgI4,. Cu2HgI4, Tl2HgI4 ... nitrogen atmosphere (200 ml/min) at a heating rate of. 5°C per min and a ..... Bates J B and Farington G C 1981 Proceedings of the interna- tional conference on fast ...

  16. TiO2/Cu2O composite based on TiO2 NTPC photoanode for photoelectrochemical (PEC) water splitting under visible light

    KAUST Repository

    Shi, Le

    2015-05-01

    Water splitting through photoelectrochemical reaction is widely regarded as a major method to generate H2 , a promising source of renewable energy to deal with the energy crisis faced up to human being. Efficient exploitation of visible light in practice of water splitting with pure TiO2 material, one of the most popular semiconductor material used for photoelectrochemical water splitting, is still challenging. One dimensional TiO2 nanotubes is highly desired with its less recombination with the short distance for charge carrier diffusion and light-scattering properties. This work is based on TiO2 NTPC electrode by the optimized two-step anodization method from our group. A highly crystalized p-type Cu2O layer was deposited by optimized pulse potentiostatic electrochemical deposition onto TiO2 nanotubes to enhance the visible light absorption of a pure p-type TiO2 substrate and to build a p-n junction at the interface to improve the PEC performance. However, because of the real photocurrent of Cu2O is far away from its theoretical limit and also poor stability in the aqueous environment, a design of rGO medium layer was added between TiO2 nanotube and Cu2O layer to enhance the photogenerated electrons and holes separation, extend charge carrier diffusion length (in comparison with those of conventional pure TiO2 or Cu2O materials) which could significantly increase photocurrent to 0.65 mA/cm2 under visible light illumination (>420 nm) and also largely improve the stability of Cu2O layer, finally lead to an enhancement of water splitting performance.

  17. Influence of resistive matrices on the stability of superconducting composites

    International Nuclear Information System (INIS)

    Maccioni, P.

    1990-03-01

    Stability of superconducting composites is governed by limiting the temperature rise in conductors submitted to disturbances. Cooling exchange enhancement and reduction of the composite mean resistivity in the normal state, introducing a sufficient amount of copper, are the main ways to ensure stabilization. Nevertheless some losses occur in composites exposed to time varying fields because of induced currents between the filaments and circulating through the matrix. These currents have to be reduced to a convenient level by increasing the matrix resistivity by means of resistive barriers of greater resistivity than copper. It is necessary to study how the existence of these barriers affects the composite stability and whether an improved arrangement may lead to the fulfillment of the required conditions e.g: stability and low losses. The original theoretical approaches allow some existing models to be completed, to evaluate additional energy dissipation, inherent in current transfer through resistive barriers, and to compare the performance of two different conductor concepts from the cryostability point of view. Numerical simulations -performed by means of a finite element code- are in quite good agreement with theoretical predictions and link up with experimental results. The influence of resistive matrix and barriers on stability degradation is clearly demonstrated by the comparison between various kinds of conductors [fr

  18. Superconductivity

    International Nuclear Information System (INIS)

    Kakani, S.L.; Kakani, Shubhra

    2007-01-01

    The monograph provides readable introduction to the basics of superconductivity for beginners and experimentalists. For theorists, the monograph provides nice and brief description of the broad spectrum of experimental properties, theoretical concepts with all details, which theorists should learn, and provides a sound basis for students interested in studying superconducting theory at the microscopic level. Special chapter on the theory of high-temperature superconductivity in cuprates is devoted

  19. Note on the cryostatic stability of superconducting composites

    International Nuclear Information System (INIS)

    Gauster, W.F.

    1978-02-01

    A careful discussion is given of the ''equal area condition'' developed by Maddock et al. In order to make the essential points as clear as possible, analytical solutions are derived under simplifying assumptions (simple model for heat transfer by nucleate and film boiling liquid helium; constant heat conduction and specific heat) instead of using more realistic but less controllable computer calculations. A quantitative definition of the concept of a long wire is given. Numerical examples for the Maddock transition characterized by the equal area condition are given for a long superconducting composite with linear cooling and for a liquid helium-cooled resistance wire of finite length. In addition, cases are shown where instead of applying the equal area stability condition, time-dependent solutions should be considered

  20. Ductile alloy and process for preparing composite superconducting wire

    Science.gov (United States)

    Verhoeven, J.D.; Finnemore, D.K.; Gibson, E.D.; Ostenson, J.E.

    An alloy for the commercial production of ductile superconducting wire is prepared by melting together copper and at least 15 weight percent niobium under non-oxygen-contaminating conditions, and rapidly cooling the melt to form a ductile composite consisting of discrete, randomly distributed and oriented dendritic-shaped particles of niobium in a copper matrix. As the wire is worked, the dendritic particles are realigned parallel to the longitudinal axis and when drawn form a plurality of very fine ductile superconductors in a ductile copper matrix. The drawn wire may be tin coated and wound into magnets or the like before diffusing the tin into the wire to react with the niobium. Impurities such as aluminum or gallium may be added to improve upper critical field characteristics.

  1. Losses in superconducting multifilament composites under alternating changing fields

    International Nuclear Information System (INIS)

    Turck, B.

    1979-03-01

    The first part of this report presents a brief review of the losses in superconducting composites in a changing external field. The losses are expressed for a single triangular shaped pulse and for a field varying exponentially with time. The losses are calculated as a function of two important time constants. The first is due to the coupling currents between the filaments, the second is due to the eddy currents induced in the matrix. In the second part of the report, the case of an oscillating sinusoidal field is considered. In particular, in a rapidly varying field, several layers of filaments can be saturated by returning currents. Complete expressions of the losses are provided together with simplified expressions which enable one to calculate the losses in most cases. In the third part, a comparison between several kinds of conductors shows that in some cases the losses are reduced by increasing the twist pitch of the conductor

  2. Method of quantitative analysis of superconducting metal-conducting composite materials

    International Nuclear Information System (INIS)

    Bogomolov, V.N.; Zhuravlev, V.V.; Petranovskij, V.P.; Pimenov, V.A.

    1990-01-01

    Technique for quantitative analysis of superconducting metal-containing composite materials, SnO 2 -InSn, WO 3 -InW, Zn)-InZn in particular, has been developed. The method of determining metal content in a composite is based on the dependence of superconducting transition temperature on alloy composition. Sensitivity of temperature determination - 0.02K, error of analysis for InSn system - 0.5%

  3. Superconductivity

    International Nuclear Information System (INIS)

    Caruana, C.M.

    1988-01-01

    Despite reports of new, high-temperature superconductive materials almost every day, participants at the First Congress on Superconductivity do not anticipate commercial applications with these materials soon. What many do envision is the discovery of superconducting materials that can function at much warmer, perhaps even room temperatures. Others hope superconductivity will usher in a new age of technology as semiconductors and transistors did. This article reviews what the speakers had to say at the four-day congress held in Houston last February. Several speakers voiced concern that the Reagan administration's apparent lack of interest in funding superconductivity research while other countries, notably Japan, continue to pour money into research and development could hamper America's international competitiveness

  4. Superconductivity

    CERN Document Server

    Ketterson, John B

    2008-01-01

    Conceived as the definitive reference in a classic and important field of modern physics, this extensive and comprehensive handbook systematically reviews the basic physics, theory and recent advances in the field of superconductivity. Leading researchers, including Nobel laureates, describe the state-of-the-art in conventional and unconventional superconductors at a particularly opportune time, as new experimental techniques and field-theoretical methods have emerged. In addition to full-coverage of novel materials and underlying mechanisms, the handbook reflects continued intense research into electron-phone based superconductivity. Considerable attention is devoted to high-Tc superconductivity, novel superconductivity, including triplet pairing in the ruthenates, novel superconductors, such as heavy-Fermion metals and organic materials, and also granular superconductors. What’s more, several contributions address superconductors with impurities and nanostructured superconductors. Important new results on...

  5. Estimate of thermoelastic heat production from superconducting composites in pulsed poloidal coil systems

    International Nuclear Information System (INIS)

    Ballou, J.K.; Gray, W.H.

    1976-01-01

    In the design of the cryogenic system and superconducting magnets for the poloidal field system in a tokamak, it is important to have an accurate estimate of the heat produced in superconducting magnets as a result of rapidly changing magnetic fields. A computer code, PLASS (Pulsed Losses in Axisymmetric Superconducting Solenoids), was written to estimate the contributions to the heat production from superconductor hysteresis losses, superconductor coupling losses, stabilizing material eddy current losses, and structural material eddy current losses. Recently, it has been shown that thermoelastic dissipation in superconducting composites can contribute as much to heat production as the other loss mechanisms mentioned above. A modification of PLASS which takes into consideration thermoelastic dissipation in superconducting composites is discussed. A comparison between superconductor thermoelastic dissipation and the other superconductor loss mechanisms is presented in terms of the poloidal coil system of the ORNL Experimental Power Reactor design

  6. New analytical results in the electromagnetic response of composite superconducting wire in parallel fields

    NARCIS (Netherlands)

    Niessen, E.M.J.; Niessen, E.M.J.; Zandbergen, P.J.

    1993-01-01

    Analytical results are presented concerning the electromagnetic response of a composite superconducting wire in fields parallel to the wire axis, using the Maxwell equations supplemented with constitutive equations. The problem is nonlinear due to the nonlinearity in the constitutive equation

  7. Solidification of Bi2Sr2Ca1Cu2Oy and Bi2Sr1.75Ca0.25CuOy

    International Nuclear Information System (INIS)

    Holesinger, T.G.; Miller, D.J.; Viswanathan, H.K.; Chumbley, L.S.

    1993-01-01

    The solidification processes for the compositions Bi 2 Sr 2 CaCu 2 O y (2212) and Bi 2 Sr 1.75 Ca 0.25 CuO y (2201) were determined as a function of oxygen partial pressure. During solidification in argon, the superconducting phases were generally not observed to form for either composition. In both cases, the solidus is lowered to approximately 750 degree C. Solidification of Bi 2 Sr 1.75 Ca 0.25 CuO y in Ar resulted in a divorced eutectic structure of Bi 2 Sr 2-x Ca x O y (22x) and Cu 2 O while solidification of Bi 2 Sr 2 CaCu 2 O y in Ar resulted in a divorced eutectic structure of Bi 2 Sr 3-x Ca x O y (23x) and Cu 2 O. Solidification of Bi 2 Sr 1.75 Ca 0.25 CuO y in O 2 resulted in large grains of 2201 interspersed with small regions containing the eutectic structure of 22x and CuO/Cu 2 O. Solidification of Bi 2 Sr 2 CaCu 2 O y in partial pressures of 1%, 20%, and 100% oxygen resulted in multiphase samples consisting of 2212, 2201, some alkaline-earth cuprates, and both divorced eutectic structures found during solidification in Ar. For both compositions, these latter structures can be attributed to oxygen deficiencies present in the melt regardless of the overpressure of oxygen. These eutectic structures are unstable and convert into the superconducting phases during subsequent anneals in oxygen. The formation process of the 2212 phase during solidification from the melt was determined to proceed through an intermediate state involving the 2201 phase

  8. The kinetics of hydrogen absorption/desorption within nanostructured composite Ni79.1Co18.6Cu2.3 alloy using resistometry

    International Nuclear Information System (INIS)

    Spasojević, M.; Maričić, A.; Ribić Zelenović, L.; Krstajić, N.; Spasojević, P.

    2013-01-01

    Highlights: ► Nanostructured Ni 79.1 Co 18.6 Cu 2.3 powder was obtained by electrochemical deposition. ► Correlation observed between electrical conductivity and absorbed hydrogen amount. ► Hydrogen absorption/desorption mechanism was determined. - Abstract: Ni 79.1 Co 18.6 Cu 2.3 powder was obtained by electrochemical deposition from an ammonium sulfate bath. The structure and surface morphology of the powder were detected by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The electrochemically obtained Ni 79.1 Co 18.6 Cu 2.3 alloy contained an amorphous phase and nanocrystals with an average size of 6.8 nm of FCC phase of the solid solution of cobalt and copper in nickel. Nanocrystals were characterized by a high average microstrain value and high minimum density of chaotically distributed dislocations. X-ray analysis also showed that powder hydrogenation at an elevated temperature of up to 200 °C did not change unit cell parameters and mean crystallite size value. SEM images show the formation of two shapes of powder particles: large cauliflower-like particles and small dendritic ones. Powder pressing at 10 MPa and at 25 °C gave samples that were analyzed for hydrogen absorption/desorption within the temperature range of 160–200 °C. Changes in electrical resistivity during absorption/desorption were monitored. The reciprocal value of resistivity (electrical conductivity) was found to increase linearly with increasing amount of absorbed hydrogen. The experimental results were used to propose an absorption/desorption mechanism. The adsorbed hydrogen molecule dissociates on alloy surface, forming adsorbed atoms. Adatoms penetrate and diffuse into the bulk of the alloy, simultaneously donating their electrons to the conduction band of the alloy. The increase in the concentration of free electrons induces a decrease in electrical resistivity. The overall absorption rate during initial absorption is determined by the

  9. The oxygen content of the high-temperature superconducting compound Bi2+xSr3-yCayCu2O8+d with respect to varying Ca and Bi contents

    International Nuclear Information System (INIS)

    Majewski, P.; Su, H.L.; Aldinger, F.

    1994-01-01

    The oxygen content of Bi 2+x Sr 3-y Ca y Cu 2 O 8+d (2212 phase) has been determined as a function of its cation concentration. With increasing Ca and Bi content the oxygen content increases and T c decreases. The oxygen content of Ca rich 2212 phase increases with decreasing annealing temperatures. The study shows that the T c of the 2212 phase primarily is controlled by its cation concentration

  10. Superconductivity

    CERN Document Server

    Poole, Charles P; Creswick, Richard J; Prozorov, Ruslan

    2014-01-01

    Superconductivity, Third Edition is an encyclopedic treatment of all aspects of the subject, from classic materials to fullerenes. Emphasis is on balanced coverage, with a comprehensive reference list and significant graphics from all areas of the published literature. Widely used theoretical approaches are explained in detail. Topics of special interest include high temperature superconductors, spectroscopy, critical states, transport properties, and tunneling. This book covers the whole field of superconductivity from both the theoretical and the experimental point of view. This third edition features extensive revisions throughout, and new chapters on second critical field and iron based superconductors.

  11. High critical temperature superconducting composite and fabrication process

    International Nuclear Information System (INIS)

    Dubots, P.; Legat, D.

    1989-01-01

    The core comprises a high temperature superconducting sintered oxide coated with alumina or barium oxide covered with a first sheath in aluminum, a second sheath in niobium and a third sheath in copper [fr

  12. Spray deposition of water-soluble multiwall carbon nanotube and Cu2ZnSnSe4 nanoparticle composites as highly efficient counter electrodes in a quantum dot-sensitized solar cell system

    Science.gov (United States)

    Zeng, Xianwei; Xiong, Dehua; Zhang, Wenjun; Ming, Liqun; Xu, Zhen; Huang, Zhanfeng; Wang, Mingkui; Chen, Wei; Cheng, Yi-Bing

    2013-07-01

    In this paper, low-cost counter electrodes (CEs) based on water-soluble multiwall carbon nanotube (MWCNT) and Cu2ZnSnSe4 nanoparticle (CZTSe NP) composites have been successfully introduced into a quantum dot-sensitized solar cell (QDSC) system. Suitable surface modification allows the MWCNTs and CZTSe NPs to be homogeneously dispersed in water, facilitating the subsequent low-temperature spray deposition of high quality composite films with different composite ratios. The electrochemical catalytic activity of the composite CEs has been critically compared by electrochemical impedance spectroscopy and Tafel-polarization analysis. It is found that the composite CE at the MWCNT : CZTSe ratio of 0.1 offers the best performance, leading to an optimal solar cell efficiency of 4.60%, which is 50.8% higher than that of the Pt reference CE. The as-demonstrated higher catalytic activity of the composite CEs compared to their single components could be ascribed to the combination of the fast electron transport of the MWCNTs and the high catalytic activity of CZTSe NPs.In this paper, low-cost counter electrodes (CEs) based on water-soluble multiwall carbon nanotube (MWCNT) and Cu2ZnSnSe4 nanoparticle (CZTSe NP) composites have been successfully introduced into a quantum dot-sensitized solar cell (QDSC) system. Suitable surface modification allows the MWCNTs and CZTSe NPs to be homogeneously dispersed in water, facilitating the subsequent low-temperature spray deposition of high quality composite films with different composite ratios. The electrochemical catalytic activity of the composite CEs has been critically compared by electrochemical impedance spectroscopy and Tafel-polarization analysis. It is found that the composite CE at the MWCNT : CZTSe ratio of 0.1 offers the best performance, leading to an optimal solar cell efficiency of 4.60%, which is 50.8% higher than that of the Pt reference CE. The as-demonstrated higher catalytic activity of the composite CEs compared to

  13. Ceramic superconductor/metal composite materials employing the superconducting proximity effect

    Science.gov (United States)

    Holcomb, Matthew J.

    2002-01-01

    Superconducting composite materials having particles of superconducting material disposed in a metal matrix material with a high electron-boson coupling coefficient (.lambda.). The superconducting particles can comprise any type of superconductor including Laves phase materials, Chevrel phase materials, A15 compounds, and perovskite cuprate ceramics. The particles preferably have dimensions of about 10-500 nanometers. The particles preferably have dimensions larger than the superconducting coherence length of the superconducting material. The metal matrix material has a .lambda. greater than 0.2, preferably the .lambda. is much higher than 0.2. The metal matrix material is a good proximity superconductor due to its high .lambda.. When cooled, the superconductor particles cause the metal matrix material to become superconducting due to the proximity effect. In cases where the particles and the metal matrix material are chemically incompatible (i.e., reactive in a way that destroys superconductivity), the particles are provided with a thin protective metal coating. The coating is chemically compatible with the particles and metal matrix material. High Temperature Superconducting (HTS) cuprate ceramic particles are reactive and therefore require a coating of a noble metal resistant to oxidation (e.g., silver, gold). The proximity effect extends through the metal coating. With certain superconductors, non-noble metals can be used for the coating.

  14. Superconductivity

    International Nuclear Information System (INIS)

    Narlikar, A.V.

    1993-01-01

    Amongst the numerous scientific discoveries that the 20th century has to its credit, superconductivity stands out as an exceptional example of having retained its original dynamism and excitement even for more than 80 years after its discovery. It has proved itself to be a rich field by continually offering frontal challenges in both research and applications. Indeed, one finds that a majority of internationally renowned condensed matter theorists, at some point of their career, have found excitement in working in this important area. Superconductivity presents a unique example of having fetched Nobel awards as many as four times to date, and yet, interestingly enough, the field still remains open for new insights and discoveries which could undeniably be of immense technological value. 1 fig

  15. Superconductivity

    International Nuclear Information System (INIS)

    Anon.

    1988-01-01

    This book profiles the research activity of 42 companies in the superconductivity field, worldwide. It forms a unique and comprehensive directory to this emerging technology. For each research site, it details the various projects in progress, analyzes the level of activity, pinpoints applications and R and D areas, reviews strategies and provides complete contact information. It lists key individuals, offers international comparisons of government funding, reviews market forecasts and development timetables and features a bibliography of selected articles on the subject

  16. Superconductivity

    International Nuclear Information System (INIS)

    Buller, L.; Carrillo, F.; Dietert, R.; Kotziapashis, A.

    1989-01-01

    Superconductors are materials which combine the property of zero electric resistance with the capability to exclude any adjacent magnetic field. This leads to many large scale applications such as the much publicized levitating train, generation of magnetic fields in MHD electric generators, and special medical diagnostic equipment. On a smaller-scale, superconductive materials could replace existing resistive connectors and decrease signal delays by reducing the RLC time constants. Thus, a computer could operate at much higher speeds, and consequently at lower power levels which would reduce the need for heat removal and allow closer spacing of circuitry. Although technical advances and proposed applications are constantly being published, it should be recognized that superconductivity is a slowly developing technology. It has taken scientists almost eighty years to learn what they now know about this material and its function. The present paper provides an overview of the historical development of superconductivity and describes some of the potential applications for this new technology as it pertains to the electronics industry

  17. Spray deposition of water-soluble multiwall carbon nanotube and Cu2ZnSnSe4 nanoparticle composites as highly efficient counter electrodes in a quantum dot-sensitized solar cell system.

    Science.gov (United States)

    Zeng, Xianwei; Xiong, Dehua; Zhang, Wenjun; Ming, Liqun; Xu, Zhen; Huang, Zhanfeng; Wang, Mingkui; Chen, Wei; Cheng, Yi-Bing

    2013-08-07

    In this paper, low-cost counter electrodes (CEs) based on water-soluble multiwall carbon nanotube (MWCNT) and Cu2ZnSnSe4 nanoparticle (CZTSe NP) composites have been successfully introduced into a quantum dot-sensitized solar cell (QDSC) system. Suitable surface modification allows the MWCNTs and CZTSe NPs to be homogeneously dispersed in water, facilitating the subsequent low-temperature spray deposition of high quality composite films with different composite ratios. The electrochemical catalytic activity of the composite CEs has been critically compared by electrochemical impedance spectroscopy and Tafel-polarization analysis. It is found that the composite CE at the MWCNT : CZTSe ratio of 0.1 offers the best performance, leading to an optimal solar cell efficiency of 4.60%, which is 50.8% higher than that of the Pt reference CE. The as-demonstrated higher catalytic activity of the composite CEs compared to their single components could be ascribed to the combination of the fast electron transport of the MWCNTs and the high catalytic activity of CZTSe NPs.

  18. Analysis of flat rolling of superconducting silver/ceramic composites

    DEFF Research Database (Denmark)

    Bech, Jakob Ilsted; Nielsen, Morten Storgård; Eriksen, Morten

    2001-01-01

    The flat rolling process from wire to tape is presumably the most crucial link in the chain of mechanical processes leading from loose powder and silver tubes to the final superconducting Ag/BSCCO tape. In order to improve the critical current density of the superconducting filaments, one must...... process these to the highest possible density without at the same time introducing failures as large cracks and macroscopic shear bands. In order to analyse and optimise the process, the interaction between the involved materials and their very different mechanical properties must be taken into account...

  19. Superconductivity

    International Nuclear Information System (INIS)

    2007-01-01

    During 2007, a large amount of the work was centred on the ITER project and related tasks. The activities based on low-temperature superconducting (LTS) materials included the manufacture and qualification of ITER full-size conductors under relevant operating conditions, the design of conductors and magnets for the JT-60SA tokamak and the manufacture of the conductors for the European dipole facility. A preliminary study was also performed to develop a new test facility at ENEA in order to test long-length ITER or DEMO full-size conductors. Several studies on different superconducting materials were also started to create a more complete database of superconductor properties, and also for use in magnet design. In this context, an extensive measurement campaign on transport and magnetic properties was carried out on commercially available NbTi strands. Work was started on characterising MgB 2 wire and bulk samples to optimise their performance. In addition, an intense experimental study was started to clarify the effect of mechanical loads on the transport properties of multi-filamentary Nb 3 Sn strands with twisted or untwisted superconducting filaments. The experimental activity on high-temperature superconducting (HTS) materials was mainly focussed on the development and characterisation of YBa 2 Cu 3 O 7-X (YBCO) based coated conductors. Several characteristics regarding YBCO deposition, current transport performance and tape manufacture were investigated. In the framework of chemical approaches for YBCO film growth, a new method, developed in collaboration with the Technical University of Cluj-Napoca (TUCN), Romania, was studied to obtain YBCO film via chemical solution deposition, which modifies the well-assessed metallic organic deposition trifluoroacetate (MOD-TFA) approach. The results are promising in terms of critical current and film thickness values. YBCO properties in films with artificially added pinning sites were characterised in collaboration with

  20. Theoretical and experimental determination of mechanical properties of superconducting composite wire

    International Nuclear Information System (INIS)

    Gray, W.H.; Sun, C.T.

    1976-07-01

    The mechanical properties of a composite superconducting (NbTi/Cu) wire are characterized in terms of the mechanical properties of each constituent material. For a particular composite superconducting wire, five elastic material constants were experimentally determined and theoretically calculated. Since the Poisson's ratios for the fiber and the matrix material were very close, there was essentially no (less than 1 percent) difference among all the theoretical predictions for any individual mechanical constant. Because of the expense and difficulty of producing elastic constant data of 0.1 percent accuracy, and therefore conclusively determining which theory is best, no further experiments were performed

  1. Superconducting characteristics of 4-Å carbon nanotube-zeolite composite

    KAUST Repository

    Lortz, Rolf W.

    2009-04-15

    We have fabricated nanocomposites consisting of 4-A carbon nanotubes embedded in the 0.7-nm pores of aluminophosphate- five (AFI) zeolite that display a superconducting specific heat transition at 15 K. MicroRaman spectra of the samples show strong and spatially uniform radial breathing mode (RBM) signals at 510 cm-1 and 550 cm-1, characteristic of the (4,2) and (5,0) nanotubes, respectively. The specific heat transition is suppressed at >2T, with a temperature dependence characteristic of finite-size effects. Comparison with theory shows the behavior to be consistent with that of a type II BCS superconductor, characterized by a coherence length of 14 ± 2 nm and a magnetic penetration length of 1.5 ± 0.7 μm. Four probe and differential resistance measurements have also indicated a superconducting transition initiating at 15 K, but the magnetoresistance data indicate the superconducting network to be inhomogeneous, with a component being susceptible to magnetic fields below 3 T and other parts capable of withstanding a magnetic field of 5Tor beyond.

  2. Phase stability, oxygen nonstoichiometry, and superconductivity properties of Bi2Sr2CaCu2O8+δ and Bi1.8Pb0.4Sr2Ca2Cu3O10+δ

    International Nuclear Information System (INIS)

    Mozhaev, A.P.; Chernyaev, S.V.; Badun, Y.V.

    1995-01-01

    Phase stability of Bi 2 Sr 2 CaCu 2 O 8+δ (2212) and Bi 1.8 Pb 0.4 Sr 2 Ca 2 Cu 3 O 10+δ (2223) was studied by means of thermogravimetry, dilatometry, high-temperature resistivity, and the powder X-ray methods in the temperature range 700-1000 degrees and at P O2 = 1-10 -4.3 atm. The existence of a high-temperature (peritectic melting) boundary of phase stability was found. The temperatures of low-temperature phase decomposition were determined in air and under an oxygen atmosphere. The change in oxygen content was determined for the 2212 phase in the temperature range 700-860 degrees C and at P O2 = 0.21-10 -3.7 atm by iodometric analysis of quenched samples. It was found that in the single-phase region, the change in oxygen nonstoichiometry had an insignificant influence on T c . It was also shown that the slow cooling of samples led to a significant decrease in T c and transport j c due to partial phase decomposition

  3. Magnetic levitation using high temperature superconducting pancake coils as composite bulk cylinders

    International Nuclear Information System (INIS)

    Patel, A; Hopkins, S C; Baskys, A; Glowacki, B A; Kalitka, V; Molodyk, A

    2015-01-01

    Stacks of superconducting tape can be used as composite bulk superconductors for both trapped field magnets and for magnetic levitation. Little previous work has been done on quantifying the levitation force behavior between stacks of tape and permanent magnets. This paper reports the axial levitation force properties of superconducting tape wound into pancake coils to act as a composite bulk cylinder, showing that similar stable forces to those expected from a uniform bulk cylinder are possible. Force creep was also measured and simulated for the system. The geometry tested is a possible candidate for a rotary superconducting bearing. Detailed finite element modeling in COMSOL Multiphysics was also performed including a full critical state model for induced currents, with temperature and field dependent properties and 3D levitation force models. This work represents one of the most complete levitation force modeling frameworks yet reported using the H-formulation and helps explain why the coil-like stacks of tape are able to sustain levitation forces. The flexibility of geometry and consistency of superconducting properties offered by stacks of tapes, make them attractive for superconducting levitation applications. (paper)

  4. Composite superconducting MgB2 wires made by continuous process

    NARCIS (Netherlands)

    Kutukcu, Mehmet; Atamert, Serdar; Scandella, Jean Louis; Hopstock, Ron; Blackwood, Alexander C.; Dhulst, Chris; Mestdagh, Jan; Nijhuis, Arend; Glowacki, Bartek A.

    Previously developed manufacturing technology of a low-cost composite single core MgB2 superconductive wires has been investigated in details using monel sheath and titanium diffusion barrier. In this process Mg and nano-sized B as well as SiC dopant powders were fed continuously to a "U" shaped

  5. Composite superconducting MgB2 wires made by continuous process

    NARCIS (Netherlands)

    Kutukcu, Mehmet; Atamert, Serdar; Scandella, Jean Louis; Hopstock, Ron; Blackwood, Alexander C.; Dhulst, Chris; Mestdagh, Jan; Nijhuis, Arend; Glowacki, Bartek A.

    2018-01-01

    Previously developed manufacturing technology of a low-cost composite single core MgB2 superconductive wires has been investigated in details using monel sheath and titanium diffusion barrier. In this process Mg and nano-sized B as well as SiC dopant powders were fed continuously to a "U" shaped

  6. Development of a new type of three-component composite superconducting wire

    International Nuclear Information System (INIS)

    Onishi, T.

    1977-01-01

    A new type of multifilamentary composite superconducting wire is described. This wire consists of seven filaments, each of which is a fine tubular Nb 50% Ti wire, filled with high purity aluminium and embedded in a cupronickel matrix. The results of experiments carried out on the stability and ac losses of this wire are presented. (author)

  7. Synthesis and electrical properties of (Pb,Co)Sr2(Y,Ca)Cu2Oz

    Science.gov (United States)

    Tashiro, T.; Maeda, T.; Abe, R.; Takechi, S.; Takahashi, T.; Haruta, M.; Horii, S.

    One of related materials to high-temperature superconductors (HTSC's) with nominal compositions of (Pb0.5Co0.5)Sr2(Y1xCax)Cu2Oz (x=0∼0.6) is synthesized and characterized. All samples are nearly single-phase, and its crystal structure is likely to be so-called "1-2-1-2" type which is one of typical structures of HTSC's. Electrical resistivity is decreased as x increases. While superconductivity is not observed at temperatures between room-temperature and 20 K for all samples, temperature dependence of the resistivity exhibits metallic behavior down to 150 K for x=0.5. Phase formation and transport behavior are discussed focusing on mixed valence-state of Co2+ and Co3+.

  8. Retrograde densification in Bi2Sr2CaCu2O8 superconductors

    International Nuclear Information System (INIS)

    Johnson, D.W. Jr.; Rhodes, W.W.

    1989-01-01

    Bi 2 Sr 2 CaCu 2 O 8 was prepared using the mixed oxide-carbonate method and sintered at temperatures ranging from 850 degrees to 911 degrees C. The samples were characterized for density, mechanical strength, phase composition, microstructure, and superconducting transition temperatures. A unique retrograde densification characteristic is demonstrated in the temperature range 850 degrees to 890 degrees C whereby the material first becomes less dense as the sintering temperature is raised, and only in a narrow temperature range from 900 degrees to 905 degrees C does the material densify then with the formation of a liquid phase. This retrograde densification, coupled with a narrow sintering range overlapping the melting temperature, makes this compound a difficult one to process

  9. Synthesis and characterization of YBaCu2O5-δ compound

    Science.gov (United States)

    Ehsandoust, A.; Sandoghchi, M.; Mokhtari, P.; Akhavan, M.

    2018-05-01

    YBaCu2O5 compound as one of the possible microstructures of Y3Ba5Cu8O19 has been synthesized. The X-ray diffraction analysis of this compound indicates that its formation is accompanied with the formation of YBa2Cu3O7-δ. The observed superconductivity around ∼92 K supports this. So, it seems that YBa2Cu3O7-δ is responsible for the observed superconductivity in YBaCu2O5, and this phase is not an independent superconducting phase. Consequently, the overall effect of the YBaCu2O5 formation during the Y3Ba5Cu8O19 fabrication process could be a reduction in Tc.

  10. MAXIMSUPER: a computer program to assist in the design of multifilamentary superconducting composites

    International Nuclear Information System (INIS)

    Hoard, R.W.; Scanlan, R.M.; Hirzel, D.G.

    1979-01-01

    The strain degradation of critical current density has been analytically and experimentally investigated for multifilamentary superconducting composites produced in a bronze core geometry. Analytic results were obtained from a computer program (MAXIMSUPER) which predicts the stresses and strains in composites as a result of thermal and axial loading. Tensile test data for Nb 3 Sn are described. It is believed that the strain dependence of the critical current found in Nb 3 Sn is due to strain enhanced martensitic transformation

  11. Chemical composition and microstructure of magnetically melt-textured Bi2Sr2Ca0.8Dy0.2Cu2O8-y

    International Nuclear Information System (INIS)

    Stassen, S.; Rulmont, A.; Krekels, T.; Ausloos, M.; Cloots, R.

    1996-01-01

    Dysprosium-doped Bi-based 2212 materials have been synthesized in the presence of a magnetic field, applied perpendicularly to the lateral face of a cylinder, by a melt-textured growth process. Thick (well oriented) layers of different chemical composition have been observed. A dysprosium-doped 2212 phase (the expected D phase) and a dysprosium-free bismuth-rich and strontium-deficient 2212 phase have been found. It is argued that the latter is a so-called M phase. Other impurity phases have been observed, connected with both 2212-type layers. A novel aspect of this work is the calcium solubility at the strontium site in the 2201 structure, and inversely the strontium solubility at the calcium site in the 8250 structure. (orig.)

  12. Composite ceramic superconducting wires for electric motor applications

    Science.gov (United States)

    Halloran, John W.

    1990-07-01

    Several types of HTSC wire have been produced and two types of HTSC motors are being built. Hundreds of meters of Ag- clad wire were fabricated from YBa2Cu3O(7-x) (Y-123) and Bi2Ca2Sr2Cu3O10 (BiSCCO). The dc homopolar motor coils are not yet completed, but multiple turns of wire have been wound on the coil bobbins to characterize the superconducting properties of coiled wire. Multifilamentary conductors were fabricated as cables and coils. The sintered polycrystalline wire has self-field critical current densities (Jc) as high as 2800 A/sq cm, but the Jc falls rapidly with magnetic field. To improve Jc, sintered YBCO wire is melt textured with a continuous process which has produced textures wire up to 0.5 meters long with 77K transport Jc above 11, 770 A/sq cm2 in self field and 2100 A/sq cm2 at 1 telsa. The Emerson Electric dc homopolar HTSC motor has been fabricated and run with conventional copper coils. A novel class of potential very powerful superconducting motors have been designed to use trapped flux in melt textures Y-123 as magnet replicas in an new type of permanent magnet motor. The stator element and part of the rotor of the first prototype machine exist, and the HTSC magnet replica segments are being fabricated.

  13. Superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Batistoni, Paola; De Marco, Francesco; Pieroni, Leonardo [ed.

    2005-07-01

    Research on superconductivity at ENEA is mainly devoted to projects related to the ITER magnet system. In this framework, ENEA has been strongly involved in the design, manufacturing and test campaigns of the ITER toroidal field model coil (TFMC), which reached a world record in operating current (up to 80 kA). Further to this result, the activities in 2004 were devoted to optimising the ITER conductor performance. ENEA participated in the tasks launched by EFDA to define and produce industrial-scale advanced Nb3Sn strand to be used in manufacturing the ITER high-field central solenoid (CS) and toroidal field (TF) magnets. As well as contributing to the design of the new strand and the final conductor layout, ENEA will also perform characterisation tests, addressing in particular the influence of mechanical stress on the Nb3Sn performance. As a member of the international ITER-magnet testing group, ENEA plays a central role in the measurement campaigns and data analyses for each ITER-related conductor and coil. The next phase in the R and D of the ITER magnets will be their mechanical characterisation in order to define the fabrication route of the coils and structures. During 2004 the cryogenic measurement campaign on the Large Hadron Collider (LHC) by-pass diode stacks was completed. As the diode-test activity was the only LHC contract to be finished on schedule, the 'Centre Europeenne pour la Recherche Nucleaire' (CERN) asked ENEA to participate in an international tender for the cold check of the current leads for the LHC magnets. The contract was obtained, and during 2004, the experimental setup was designed and realised and the data acquisition system was developed. The measurement campaign was successfully started at the end of 2004 and will be completed in 2006.

  14. Phase conversion from hexagonal CuS(y)Se(1-y) to cubic Cu(2-x)S(y)Se(1-y): composition variation, morphology evolution, optical tuning, and solar cell applications.

    Science.gov (United States)

    Xu, Jun; Yang, Xia; Yang, Qingdan; Zhang, Wenjun; Lee, Chun-Sing

    2014-09-24

    In this work, we report a simple and low-temperature approach for the controllable synthesis of ternary Cu-S-Se alloys featuring tunable crystal structures, compositions, morphologies, and optical properties. Hexagonal CuS(y)Se(1-y) nanoplates and face centered cubic (fcc) Cu(2-x)S(y)Se(1-y) single-crystal-like stacked nanoplate assemblies are synthesized, and their phase conversion mechanism is well investigated. It is found that both copper content and chalcogen composition (S/Se atomic ratio) of the Cu-S-Se alloys are tunable during the phase conversion process. Formation of the unique single-crystal-like stacked nanoplate assemblies is resulted from oriented stacking coupled with the Ostwald ripening effect. Remarkably, optical tuning for continuous red shifts of both the band-gap absorption and the near-infrared localized surface plasmon resonance are achieved. Furthermore, the novel Cu-S-Se alloys are utilized for the first time as highly efficient counter electrodes (CEs) in quantum dot sensitized solar cells (QDSSCs), showing outstanding electrocatalytic activity for polysulfide electrolyte regeneration and yielding a 135% enhancement in power conversion efficiency (PCE) as compared to the noble metal Pt counter electrode.

  15. Ultrasensitive interplay between ferromagnetism and superconductivity in NbGd composite thin films

    Science.gov (United States)

    Bawa, Ambika; Gupta, Anurag; Singh, Sandeep; Awana, V. P. S.; Sahoo, Sangeeta

    2016-01-01

    A model binary hybrid system composed of a randomly distributed rare-earth ferromagnetic (Gd) part embedded in an s-wave superconducting (Nb) matrix is being manufactured to study the interplay between competing superconducting and ferromagnetic order parameters. The normal metallic to superconducting phase transition appears to be very sensitive to the magnetic counterpart and the modulation of the superconducing properties follow closely to the Abrikosov-Gor’kov (AG) theory of magnetic impurity induced pair breaking mechanism. A critical concentration of Gd is obtained for the studied NbGd based composite films (CFs) above which superconductivity disappears. Besides, a magnetic ordering resembling the paramagnetic Meissner effect (PME) appears in DC magnetization measurements at temperatures close to the superconducting transition temperature. The positive magnetization related to the PME emerges upon doping Nb with Gd. The temperature dependent resistance measurements evolve in a similar fashion with the concentration of Gd as that with an external magnetic field and in both the cases, the transition curves accompany several intermediate features indicating the traces of magnetism originated either from Gd or from the external field. Finally, the signatures of magnetism appear evidently in the magnetization and transport measurements for the CFs with very low (<1 at.%) doping of Gd.

  16. A two-storey structured photoanode of a 3D Cu2ZnSnS4/CdS/ZnO@steel composite nanostructure for efficient photoelectrochemical hydrogen generation

    Science.gov (United States)

    Choi, Youngwoo; Baek, Minki; Zhang, Zhuo; Dao, Van-Duong; Choi, Ho-Suk; Yong, Kijung

    2015-09-01

    A two-storey structured photoanode of a 3D Cu2ZnSnS4(CZTS)/CdS/ZnO@steel composite nanostructure has been fabricated by using the solution method and demonstrated highly efficient photoelectrochemical hydrogen generation due to its contraption in the structure for sufficient light absorption as well as the three step-down band alignments for efficient charge separation and transport. This composite structure is composed of two storeys: the upper storey is the CZTS/CdS/ZnO hetero-nanorods (NRs) covered on the stainless steel mesh; the bottom storey is the CZTS/CdS/ZnO hetero-NRs grown on the FTO glass. The CZTS/CdS/ZnO hetero-NRs have cascade band gaps decreasing from 3.15 to 1.82 eV, which gives them efficient charge transfer and broad photoresponse in the UV to near-IR region, resulting in 47% IPCE in a wide light region from 400 to 500 nm; and the stainless steel mesh serves not only as a conductor for charge transport, but also as a skeleton of the grid structure for absorbing more light. The related mechanism has been investigated, which demonstrates that the two-storey CZTS/CdS/ZnO@steel composite nanostructure would have great potential as a promising photoelectrode with high efficiency and low cost for PEC hydrogen generation.A two-storey structured photoanode of a 3D Cu2ZnSnS4(CZTS)/CdS/ZnO@steel composite nanostructure has been fabricated by using the solution method and demonstrated highly efficient photoelectrochemical hydrogen generation due to its contraption in the structure for sufficient light absorption as well as the three step-down band alignments for efficient charge separation and transport. This composite structure is composed of two storeys: the upper storey is the CZTS/CdS/ZnO hetero-nanorods (NRs) covered on the stainless steel mesh; the bottom storey is the CZTS/CdS/ZnO hetero-NRs grown on the FTO glass. The CZTS/CdS/ZnO hetero-NRs have cascade band gaps decreasing from 3.15 to 1.82 eV, which gives them efficient charge transfer and broad

  17. Quenching effect on properties of Bi-Sr-Ca-Cu-O superconducting ceramics of various composition

    International Nuclear Information System (INIS)

    Amitin, E.B.; Gromilov, S.A.; Naumov, V.N.; Royak, A.Ya.; Starikov, M.A.

    1989-01-01

    Bismuth ceramics quenching effect on superconducting properties of samples of various composition is investigated. Two types of quenching effect on sample properties are detected: an increase of superconducting transition temperature T c by 15-20 K; broadening of temperature interval of the phase transition without anynatable T c displacement. X ray diffraction investigations have not detected sufficient differences in diffraction patterns of quenched and non-quenched samples. Within the limits of composition analysis by oxygen (±3%) no change of its content prior to and after quenching is detected. A correlation between the presence of an amorphous phase in a sample and the type of quenching effect is observed: T c increases in ceramics where an amorphous component is detected

  18. Method of forming a ceramic superconducting composite wire using a molten pool

    International Nuclear Information System (INIS)

    Geballe, T.H.; Feigelson, R.S.; Gazit, D.

    1991-01-01

    This paper describes a method for making a flexible superconductive composite wire. It comprises: drawing a wire of noble metal through a molten material, formed by melting a solid formed by pressing powdered Bi 2 O 3 , CaCO 3 SrCO 3 and CuO in a ratio of components necessary for forming a Bi-Sr-Ca-Cu-O superconductor, into the solid and sintering at a temperature in the range of 750 degrees - 800 degrees C. for 10-20 hours, whereby the wire is coated by the molten material; and cooling the coated wire to solidify the molten material to form the superconductive flexible composite wire without need of further annealing

  19. Raman-scattering results from Y1-xCaxSr2Cu2GaO7

    International Nuclear Information System (INIS)

    Salamon, D.; Liu, R.; Klein, M.V.; Groenke, D.A.; Poeppelmeier, K.R.; Dabrowski, B.; Han, P.D.; Payne, D.A.

    1993-01-01

    We present a Raman-scattering study of Y 1-x Ca x Sr 2 Cu 2 GaO 7 for both the x=0 parent compound and doped compositions with x=0.25 and x=0.40. Extrapolation from YBa 2 Cu 3 O 7-d and other cuprates allows us to assign many of the Raman-active phonon modes in the x=0 material, as well as identify a two-magnon scattering peak, a second-order phonon scattering peak, and a Raman continuum out to 4000 cm -1 . Despite compositional inhomogeneities, the doped superconducting samples show some of the same low-energy phonon features as the x=0 material. There is, however, a doping-dependent shift in the positions of features in the 500--700 cm -1 range, possibly due to Ca locating on Sr sites instead of Y sites. The relative intensities of the phonon peaks in the doped material are also changed from the insulator (x=0), suggesting that a resonant Raman phenomenon is occurring. The temperature-dependent spectra show what appears to be a superconducting dip in the background intensity, but the low superconducting fractions in these samples make this difficult to verify. The doped material also has a Raman continuum out to 4000 cm -1 just as in the x=0 samples, but with the two-magnon and second-order phonon scattering peaks significantly reduced in intensity. This may be a result of changes in the long-range ordering, or another manifestation of the same resonance phenomena occurring at lower energies. Single-crystal samples of the doped material Y 1-x Ca x Sr 2 Cu 2 GaO 7 are necessary for a more conclusive Raman study

  20. Magnetic properties and superconducting-fluctuation diamagnetism above Tc in Bi2-xPbxSr2CaCu2O8+δ (x=0.0, 0.1, 0.2, 0.3, 0.5) and

    International Nuclear Information System (INIS)

    Lee, W.C.; Cho, J.H.; Johnston, D.C.

    1991-01-01

    The magnetic susceptibilities χ(T) of the title compounds above and below T c are reported. For the Bi 2-x Pb x Sr 2 CaCu 2 O 8+δ (Bi 2:2:1:2) system, optimization of the phase purity and superconducting properties is found between x=0.2 and 0.3. The χ(T) data for these Bi 2:2:1:2 and for the two Bi 2:2:2:3 samples increase monotonically with temperature from T c up to at least 400 K, exhibiting strong negative curvature below ∼200 K. From theoretical fits to the data in the two-dimensional regime above T c using the static Lawrence-Doniach model as modified by Klemm, we conclude that the negative curvature in χ(T) for each sample arises from superconducting-fluctuation diamagnetism (SFD). The data are thus consistent with a superconducting order parameter of s-wave symmetry. From the fits to the data, the Ginzburg-Landau coherence lengths in the CuO 2 planes were obtained and found to be ξ ab (0)=20.4(2) A for Bi 2:2:1:2 and 11.8(4) A for Bi 2:2:2:3. The value for Bi 2:2:1:2 is comparable to those calculated from upper critical magnetic-field data for this compound (23.5--27.1 A). Our ξ ab (0) values for Bi 2:2:1:2 and Bi 2:2:2:3 are also comparable with that (13.6 A) found from our previous similar analysis of the SFD in YBa 2 Cu 3 O 7 . The possible role of the bridging oxygens out of the CuO 2 plane in Bi 2:2:2:3 and the influence of the dynamics in the fits to the SFD in the Bi-based compounds remain to be addressed

  1. Crossover from BCS to composite boson (local pair) superconductivity in quasi-2D systems

    International Nuclear Information System (INIS)

    Gorbar, E.V.; Loktev, V.M.; Sharapov, S.G.

    1995-01-01

    The crossover from cooperative Cooper pairing to independent bound state (composite bosons) formation and condensation in quasi-2 D systems is studied. It is shown that at low carrier density the critical superconducting temperature is equal to the temperature of Bose-condensation of ideal quasi-2 D Bose-gas with heavy dynamical mass, meanwhile at high densities the BCS result remains valid. 15 refs

  2. Ceramic/metal and A15/metal superconducting composite materials exploiting the superconducting proximity effect and method of making the same

    International Nuclear Information System (INIS)

    Holcomb, M.J.

    1999-01-01

    A composite superconducting material made of coated particles of ceramic superconducting material and a metal matrix material is disclosed. The metal matrix material fills the regions between the coated particles. The coating material is a material that is chemically nonreactive with the ceramic. Preferably, it is silver. The coating serves to chemically insulate the ceramic from the metal matrix material. The metal matrix material is a metal that is susceptible to the superconducting proximity effect. Preferably, it is a NbTi alloy. The metal matrix material is induced to become superconducting by the superconducting proximity effect when the temperature of the material goes below the critical temperature of the ceramic. The material has the improved mechanical properties of the metal matrix material. Preferably, the material consists of approximately 10% NbTi, 90% coated ceramic particles (by volume). Certain aspects of the material and method will depend upon the particular ceramic superconductor employed. An alternative embodiment of the invention utilizes A15 compound superconducting particles in a metal matrix material which is preferably a NbTi alloy

  3. Ceramic/metal and A15/metal superconducting composite materials exploiting the superconducting proximity effect and method of making the same

    Science.gov (United States)

    Holcomb, Matthew J.

    1999-01-01

    A composite superconducting material made of coated particles of ceramic superconducting material and a metal matrix material. The metal matrix material fills the regions between the coated particles. The coating material is a material that is chemically nonreactive with the ceramic. Preferably, it is silver. The coating serves to chemically insulate the ceramic from the metal matrix material. The metal matrix material is a metal that is susceptible to the superconducting proximity effect. Preferably, it is a NbTi alloy. The metal matrix material is induced to become superconducting by the superconducting proximity effect when the temperature of the material goes below the critical temperature of the ceramic. The material has the improved mechanical properties of the metal matrix material. Preferably, the material consists of approximately 10% NbTi, 90% coated ceramic particles (by volume). Certain aspects of the material and method will depend upon the particular ceramic superconductor employed. An alternative embodiment of the invention utilizes A15 compound superconducting particles in a metal matrix material which is preferably a NbTi alloy.

  4. Ag doped (Bi1.6Pb0.4Sr2CaCu2O8+δ textured rods

    Directory of Open Access Journals (Sweden)

    Díez, J. C.

    2008-06-01

    Full Text Available In this work, superconducting samples of (Bi1.6Pb0.4Sr2CaCu2O8+δ with Ag additions have been studied. (Bi1.6Pb0.4Sr2CaCu2O8+δ + x wt.% Ag (with x = 0, 1 and 3 powders were synthesized using a sol-gel method. The obtained powders were used as precursors to fabricate long textured cylindrical bars through a floating zone melting method. A drastic change on the microstructure has been found when comparing with undoped Bi2Sr2CaCu2O8+δ samples. The results showed that electrical resistivity at room temperature, critical current as well as flexural strength are improved when Ag is added to these Pb doped samples, while critical temperature does not change. On the other hand, it has been found that samples with composition (Bi1.6Pb0.4Sr2CaCu2O8+δ + Ag shown E-I curves with very high sharpness values on the zone of the superconducting to normal transition, reaching n-values (E∼In as high as 45 at 65K.Se han preparado polvos cerámicos de composición (Bi1.6Pb0.4Sr2CaCu2O8+δ + x % Ag en peso (con x = 0, 1 y 3 mediante un proceso sol-gel. Estos polvos se han utilizado para fabricar precursores que se texturaron por medio del método de fusión zonal flotante. Se ha encontrado un gran cambio en la microestructura cuando se compara con muestras de composición pura Bi2Sr2CaCu2O8+δ. Tanto la resistividad eléctrica a temperatura ambiente, como la corriente crítica, así como la resistencia a flexión se mejoran cuando la Ag se adiciona a estas muestras dopadas con Pb, mientras que no se observa cambio en la temperatura crítica. Por otra parte, se ha encontrado que las muestras de composición (Bi1.6Pb0.4Sr2CaCu2O8+δ + Ag presentan una gran pendiente de la curva E-I en la zona de transición entre el estado superconductor y el estado normal. Con estas composiciones, se han encontrado valores de n (E∼In de hasta 45 a 65K.

  5. Use of neutron diffraction in determining strains in high-temperaure superconducting composites

    International Nuclear Information System (INIS)

    Hitterman, R.L.; Faber, J. Jr.; Kupperman, D.S.; Singh, J.P.; Majumdar, S.

    1990-01-01

    The Argonne Intense Pulsed Neutron Source and General Purpose Powder Diffractometer have been used to study high T c metal oxide composites composed of yttrium barium copper oxide and silver. Neutron diffraction techniques were applied to composites with 15, 20 and 30% silver content by volume. The authors have observed that after hot pressing, the 30% Ag specimens contained both orthorhombic high T c and tetragonal, non-superconducting phases near the center of the specimens but only tetragonal near the surface. The relationship of shifts in Bragg peaks to strains of the constituents is discussed

  6. Magnetization of in situ multifilamentary superconducting Nb3Sn-Cu composites

    International Nuclear Information System (INIS)

    Shen, S.S.; Verhoeven, J.D.

    1980-01-01

    Magnetic properties are reported for in situ superconducting Nb 3 Sn composites that have exhibited attractive electrical properties and superior mechanical characteristics. Magnetization measurements were conducted up to 4 T at 4.2 K on a variety of samples of different sizes and twist pitches, and the results are presented in absolute M-H curves and losses per cycle. It is observed that the magnetization of such composites is generally proportional to the size of the wire (approx. 0.25 to 0.51 mm) rather than the fiber size (approx. 10 -7 m), which indicates a strong coupling effect among Nb 3 Sn fibers

  7. Hierarchical Cu2O foam/g-C3N4 photocathode for photoelectrochemical hydrogen production

    Science.gov (United States)

    Ma, Xinzhou; Zhang, Jingtao; Wang, Biao; Li, Qiuguo; Chu, Sheng

    2018-01-01

    Solar photoelectrochemical (PEC) hydrogen production is a promising way for solving energy and environment problems. Earth-abundant Cu2O is a potential light absorber for PEC hydrogen production. In this article, hierarchical porous Cu2O foams are prepared by thermal oxidation of the electrochemically deposited Cu foams. PEC performances of the Cu2O foams are systematically studied and discussed. Benefiting from their higher light harvesting and more efficient charge separation, the Cu2O foams demonstrate significantly enhanced photocurrents and photostability compared to their film counterparts. Moreover, by integrating g-C3N4, hierarchical Cu2O foam/g-C3N4 composites are prepared with further improved photocurrent and photostability, appearing to be potential photocathodes for solar PEC hydrogen production. This study may provide a new and useful insight for the development of Cu2O-based photocathodes for PEC hydrogen production.

  8. Cu2O-based solar cells using oxide semiconductors

    International Nuclear Information System (INIS)

    Minami, Tadatsugu; Nishi, Yuki; Miyata, Toshihiro

    2016-01-01

    We describe significant improvements of the photovoltaic properties that were achieved in Al-doped ZnO (AZO)/n-type oxide semiconductor/p-type Cu 2 O heterojunction solar cells fabricated using p-type Cu 2 O sheets prepared by thermally oxidizing Cu sheets. The multicomponent oxide thin film used as the n-type semiconductor layer was prepared with various chemical compositions on non-intentionally heated Cu 2 O sheets under various deposition conditions using a pulsed laser deposition method. In Cu 2 O-based heterojunction solar cells fabricated using various ternary compounds as the n-type oxide thin-film layer, the best photovoltaic performance was obtained with an n-ZnGa 2 O 4 thin-film layer. In most of the Cu 2 O-based heterojunction solar cells using multicomponent oxides composed of combinations of various binary compounds, the obtained photovoltaic properties changed gradually as the chemical composition was varied. However, with the ZnO-MgO and Ga 2 O 3 -Al 2 O 3 systems, higher conversion efficiencies (η) as well as a high open circuit voltage (V oc ) were obtained by using a relatively small amount of MgO or Al 2 O 3 , e.g., (ZnO) 0.91 –(MgO) 0.09 and (Ga 2 O 3 ) 0.975 –(Al 2 O 3 ) 0.025 , respectively. When Cu 2 O-based heterojunction solar cells were fabricated using Al 2 O 3 –Ga 2 O 3 –MgO–ZnO (AGMZO) multicomponent oxide thin films deposited with metal atomic ratios of 10, 60, 10 and 20 at.% for the Al, Ga, Mg and Zn, respectively, a high V oc of 0.98 V and an η of 4.82% were obtained. In addition, an enhanced η and an improved fill factor could be achieved in AZO/n-type multicomponent oxide/p-type Cu 2 O heterojunction solar cells fabricated using Na-doped Cu 2 O (Cu 2 O:Na) sheets that featured a resistivity controlled by optimizing the post-annealing temperature and duration. Consequently, an η of 6.25% and a V oc of 0.84 V were obtained in a MgF 2 /AZO/n-(Ga 2 O 3 –Al 2 O 3 )/p-Cu 2 O:Na heterojunction solar cell fabricated using

  9. Cu2O-based solar cells using oxide semiconductors

    Science.gov (United States)

    Minami, Tadatsugu; Nishi, Yuki; Miyata, Toshihiro

    2016-01-01

    We describe significant improvements of the photovoltaic properties that were achieved in Al-doped ZnO (AZO)/n-type oxide semiconductor/p-type Cu2O heterojunction solar cells fabricated using p-type Cu2O sheets prepared by thermally oxidizing Cu sheets. The multicomponent oxide thin film used as the n-type semiconductor layer was prepared with various chemical compositions on non-intentionally heated Cu2O sheets under various deposition conditions using a pulsed laser deposition method. In Cu2O-based heterojunction solar cells fabricated using various ternary compounds as the n-type oxide thin-film layer, the best photovoltaic performance was obtained with an n-ZnGa2O4 thin-film layer. In most of the Cu2O-based heterojunction solar cells using multicomponent oxides composed of combinations of various binary compounds, the obtained photovoltaic properties changed gradually as the chemical composition was varied. However, with the ZnO-MgO and Ga2O3-Al2O3 systems, higher conversion efficiencies (η) as well as a high open circuit voltage (Voc) were obtained by using a relatively small amount of MgO or Al2O3, e.g., (ZnO)0.91-(MgO)0.09 and (Ga2O3)0.975-(Al2O3)0.025, respectively. When Cu2O-based heterojunction solar cells were fabricated using Al2O3-Ga2O3-MgO-ZnO (AGMZO) multicomponent oxide thin films deposited with metal atomic ratios of 10, 60, 10 and 20 at.% for the Al, Ga, Mg and Zn, respectively, a high Voc of 0.98 V and an η of 4.82% were obtained. In addition, an enhanced η and an improved fill factor could be achieved in AZO/n-type multicomponent oxide/p-type Cu2O heterojunction solar cells fabricated using Na-doped Cu2O (Cu2O:Na) sheets that featured a resistivity controlled by optimizing the post-annealing temperature and duration. Consequently, an η of 6.25% and a Voc of 0.84 V were obtained in a MgF2/AZO/n-(Ga2O3-Al2O3)/p-Cu2O:Na heterojunction solar cell fabricated using a Cu2O:Na sheet with a resistivity of approximately 10 Ω·cm and a (Ga0.975Al0

  10. Controlled preparation of Ag–Cu2O nanocorncobs and their enhanced photocatalytic activity under visible light

    International Nuclear Information System (INIS)

    Yang, Siyuan; Zhang, Shengsen; Wang, Hongjuan; Yu, Hao; Fang, Yueping; Peng, Feng

    2015-01-01

    Graphical abstract: The corncob-like Ag–Cu 2 O nanostructure with suitably exposed Ag surface exhibited much higher photocatalytic activity than Ag@Cu 2 O nanocables and Cu 2 O nanowires. - Highlights: • Ag–Cu 2 O nanocorncobs have been controllably prepared by a simple synthesis. • The possible formation mechanism of Ag–Cu 2 O has been studied. • Ag–Cu 2 O exhibits noticeable improved photocurrent compared with the pure Cu 2 O NWs. • Ag–Cu 2 O with suitably exposed Ag surface shows much higher photocatalytic activity. - Abstract: Novel corncob-like nano-heterostructured Ag–Cu 2 O photocatalyst has been controllably prepared by adjusting the synthetic parameters, and the possible formation mechanism has been also studied. The photoelectrochemical and photocatalytic performances demonstrated that the as-prepared Ag–Cu 2 O nanocorncobs exhibited higher photocatalytic activity than both pure Cu 2 O nanowires and cable-like Ag@Cu 2 O nano-composites. It was concluded that Ag–Cu 2 O nanocorncobs with suitably exposed Ag surface not only effectively inhibit the recombination of electron–hole pairs but also suitably increase the active sites of electronic conduction, and thus increasing the photocatalytic activity under visible light irradiation

  11. Research of mechanical and void properties of composite insulation for superconducting busbar

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Xiongyi, E-mail: huangxy@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Li, Guoliang [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Clayton, Nicholas [ITER IO, Superconductor Systems & Auxiliaries Section, 13067 St Paul Lez Durance Cedex (France); Lu, Kun; Wang, Chunyu; Wang, Chao; Dai, Zhiheng [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Gung, Chen-yu; Devred, Arnaud [ITER IO, Superconductor Systems & Auxiliaries Section, 13067 St Paul Lez Durance Cedex (France); Song, Yuntao; Fang, Linlin [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2017-01-15

    Highlights: • Two curing methods for the pre-preg on the superconducting busbar are researched. • Vaccum bag and silicone rubber is used for pre-preg curing as complement of VPI in fusion filed. • The results of mechanical properties and void content is described and discussed. - Abstract: Pre-preg material has been widely-used in the industry of the aerospace, the wind power, which has many advantages on manufacture process, and can be chosen as an effective complementary insulation method for the Wet-winding and Vacuum Pressure Impregnation technology in the field of superconducting fusion magnets. ASIPP undertaken many engineering tasks on the superconducting coil and busbar design and manufacture for the large fusion device, the pre-preg material and the relevant curing technology were researched as a new method for the high voltage potential components in ITER Feeders, such as the busbars and current leads. Two types of Chinese industrial glass fiber pre-preg insulation composite material were studied and pre-qualified using vacuum bag and silicone rubber assistance technique in ASIPP. The mechanical properties including the ILSS and UTS at 77 K, and void content of this composites were measured and discussed in this paper in detail.

  12. An investigation of the element composition of superconducting ceramics by neutron activation and radiography methods

    International Nuclear Information System (INIS)

    Kist, A.A.; Flitsiyan, E.S.

    1994-01-01

    The neutron activation methods for determining the general composition and distribution of the main components in HTSC ceramics were developed. The conditions for the reduction of the analysis error were discussed. The dependences of the oxygen content and superconducting parameters of single-phase and polyphase yttrium ceramics on the regime of heat treatment in air were investigated. Variation in the oxygen content was found to have a nonmonotone character, depending on the temperature of quenching and annealing. Correlation between the character of the superconducting transition and the oxygen content was observed. During the heat treatment, reversible structural phase transitions proceed in the single-phase ceramics in the polyphase ceramics, the recrystallization processes occur, which result in homogenization of its structure

  13. Superconducting properties of powder-metallurgically produced Cu-Nb3Sn composite wires

    International Nuclear Information System (INIS)

    Schaper, W.; Wecker, J.; Heine, K.; Bormann, R.; Freyhardt, H.C.

    1988-01-01

    The critical current density of composite superconducting wires can be improved by ternary or quaternary additions. If these additions are incorporated into the A15 phase the upper critical field can be increased. An increase in this field, however, can only be realized if the additions do not strongly deteriorate the critical temperature. An enhanced upper critical field in connection with a favorable grain size of the A15 phase finally leads to improved critical current densities in the entire field range. With these parameters as guidelines, the effects of Ti, In, Ga, and Ge additions to the bronze and of Ta additions to the niobium on the superconducting properties of PM produced Cu-Nb 3 Sn wires were investigated

  14. The self-field effect in twisted superconducting composites

    International Nuclear Information System (INIS)

    Duchateau, J.L.; Turck, B.; Krempasky, L.; Polak, M.

    1976-01-01

    Since twisting of composites does not cause a transposition with respect to the self-field of the transport current, they behave like a bulk superconductor with averaged critical current density, when the transport current is changed. Consequently, the electric field is given by the history of the transport current changes. Using a simplified model (Jsub(c) = const) the expressions for the electric fields and losses for the first and immediately following second increase of the transport current are derived. Experimental results are also presented which clearly show higher electric field during the first run than during the following, which agrees with theoretical predictions. Quite a good quantitative agreement between theory and experiment was obtained up to about 80 % of the critical transport current. The influence of the copper matrix is also discussed. (author)

  15. Facile synthesis of core-shell Cu2O@ ZnO structure with enhanced photocatalytic H2 production

    Science.gov (United States)

    Zhang, Yong-Hui; Jiu, Bei-Bei; Gong, Fei-Long; Lu, Kuan; Jiang, Nan; Zhang, Hao-Li; Chen, Jun-Li

    2018-05-01

    Core-shell Cu2O@ZnO composites were synthesized successfully based on a one-pot hydrothermal method in the presence of dioctyl sulfosuccinate sodium salt (AOT) surfactant. The Cu2O can be converted to rough core-shell Cu2O@ZnO structure by adjusting the amount of zinc powder added. The as-synthesized Cu2O@ZnO composites exhibited excellent photocatalytic activity and the amount of H2 generated using these composites was 4.5-fold more than that produced with Cu2O cubes. A possible photocatalytic mechanism for the Cu2O@ZnO composites with enhanced photocatalytic activity could be the separation by ZnO of the effective charge carriers.

  16. Fabrication of extruded wire of MgB2/Al composite material and its superconducting property and microstructure

    Czech Academy of Sciences Publication Activity Database

    Matsuda, K.; Nishimura, K.; Ikeno, S.; Mori, K.; Aoyama, S.; Yabumoto, Y.; Hishinuma, Y.; Müllerová, Ilona; Frank, Luděk; Yurchenko, V. V.; Johansen, T. H.

    2008-01-01

    Roč. 97, - (2008), 012230:1-6 E-ISSN 1742-6596. [European Conference on Applied Superconductivity /8./ - EUCAS 2007. Brussels, 16.09.2007-20.09.2007] Institutional research plan: CEZ:AV0Z20650511 Keywords : MgB2/Al composite * superconductors * electron microscopy Subject RIV: JI - Composite Materials

  17. Cu2O-directed in situ growth of Au nanoparticles inside HKUST-1 nanocages.

    Science.gov (United States)

    Liu, Yongxin; Liu, Ting; Tian, Long; Zhang, Linlin; Yao, Lili; Tan, Taixing; Xu, Jin; Han, Xiaohui; Liu, Dan; Wang, Cheng

    2016-12-07

    Controllable integration of metal nanoparticles (MNPs) and metal-organic frameworks (MOFs) is attracting considerable attention as the obtained composite materials always show synergistic effects in applications of catalysis, delivery, as well as sensing. Herein, a Cu 2 O-directed in situ growth strategy was developed to integrate Au nanoparticles and HKUST-1. In this strategy, Cu 2 O@HKUST-1 core-shell heterostructures, HKUST-1 nanocages, Cu 2 O@Au@HKUST-1 sandwich core-shell heterostructures and Au@HKUST-1 balls-in-cage heterostructures were successfully synthesized. Cu 2 O@HKUST-1 core-shell heterostructures were synthesized by soaking Cu 2 O nanocrystals in benzene-1,3,5-tricarboxylic acid solution. The well-defined Cu 2 O@HKUST-1 core-shell heterostructures were demonstrated to be dominated by the ratio of Cu 2+ cations to btc 3- ligands in solution during the period of HKUST-1 formation. Cu 2 O@Au@HKUST-1 sandwich core-shell or Au@HKUST-1 balls-in-cage heterostructures were obtained by impregnating HAuCl 4 into Cu 2 O@HKUST-1 core-shell heterostructures. Due to the porosity of HKUST-1 and reducibility of Cu 2 O, HAuCl 4 could pass through the HKUST-1 shell and be reduced by the Cu 2 O core in situ forming Au nanoparticles. Finally, CO oxidation reaction at high temperatures was carried out to assess the catalytic functionality of the obtained composite heterostructures. This strategy can circumvent some drawbacks of the existing approaches for integrating MNPs and MOFs, such as nonselective deposition of MNPs at the outer surface of the MOF matrices, extreme treatment conditions and additional surface modifications.

  18. Elastic stiffnesses of an Nb-Ti/Cu-composite superconductive wire

    Science.gov (United States)

    Kim, Sudook; Ledbetter, Hassel; Ogi, Hirotsugu

    2000-09-01

    Elastic-stiffness coefficients were determined on a 1.4-mm-diameter wire consisting of superconducting Nb-Ti fibers in a copper matrix, with a polyvinyl-resin coating. The matrix contained 324 Nb-Ti fibers. An electromagnetic-acoustic-resonance method was used to obtain five independent elastic-stiffness coefficients assuming transverse-isotropic symmetry. From these we calculated Young moduli, bulk modulus, and principal Poisson ratios. As a check, we used a mechanical-impulse-excitation method to directly measure the Young modulus in the fiber direction. The three-phase composite wire showed a 10% anisotropy in the Young modulus.

  19. EPR of CU+2:Mb single crystal

    International Nuclear Information System (INIS)

    Nascimento, O.R.; Ribeiro, S.C.; Bemski, G.

    1976-01-01

    Copper introduced into met-myoglobin crystals occupies various sites as indicated by EPR parameters. CU 2+ (A) is probably liganded to histidine A10, lysine A14 and asparagine GH4 (Banaszak, 1965) and shows super-hyperfine interaction with a single (imidazole) nitrogen. Cu 2+ (B) and Cu 2+ (C) correspond to other anisotropic sites described with lesser details. Cu 2+ (A) exhibits a transition to an isotropic form with a transition temperature of 40.5 0 C. This transition is indicative of a conformational change in myoglobin and could correspond to a motion of A helix away from the GH section. The transition temperature is 7 0 C higher than the previously reported (Atanasov, 1971) one for myoglobin in solution

  20. Superconducting cermets

    International Nuclear Information System (INIS)

    Goyal, A.; Funkenbusch, P.D.; Chang, G.C.S.; Burns, S.J.

    1988-01-01

    Two distant classes of superconducting cermets can be distinguished, depending on whether or not a fully superconducting skeleton is established. Both types of cermets have been successfully fabricated using non-noble metals, with as high as 60wt% of the metal phase. The electrical, magnetic and mechanical behavior of these composites is discussed

  1. Reduced graphene oxide wrapped Cu2O supported on C3N4: An efficient visible light responsive semiconductor photocatalyst

    Directory of Open Access Journals (Sweden)

    S. Ganesh Babu

    2015-10-01

    Full Text Available Herein, Cu2O spheres were prepared and encapsulated with reduced graphene oxide (rGO. The Cu2O–rGO–C3N4 composite covered the whole solar spectrum with significant absorption intensity. rGO wrapped Cu2O loading caused a red shift in the absorption with respect to considering the absorption of bare C3N4. The photoluminescence study confirms that rGO exploited as an electron transport layer at the interface of Cu2O and C3N4 heterojunction. Utmost, ∼2 fold synergistic effect was achieved with Cu2O–rGO–C3N4 for the photocatalytic reduction of 4-nitrophenol to 4-aminophenol in comparison with Cu2O–rGO and C3N4. The Cu2O–rGO–C3N4 photocatalyst was reused for four times without loss in its activity.

  2. Reduced graphene oxide wrapped Cu2O supported on C3N4: An efficient visible light responsive semiconductor photocatalyst

    Science.gov (United States)

    Ganesh Babu, S.; Vinoth, R.; Surya Narayana, P.; Bahnemann, Detlef; Neppolian, B.

    2015-10-01

    Herein, Cu2O spheres were prepared and encapsulated with reduced graphene oxide (rGO). The Cu2O-rGO-C3N4 composite covered the whole solar spectrum with significant absorption intensity. rGO wrapped Cu2O loading caused a red shift in the absorption with respect to considering the absorption of bare C3N4. The photoluminescence study confirms that rGO exploited as an electron transport layer at the interface of Cu2O and C3N4 heterojunction. Utmost, ˜2 fold synergistic effect was achieved with Cu2O-rGO-C3N4 for the photocatalytic reduction of 4-nitrophenol to 4-aminophenol in comparison with Cu2O-rGO and C3N4. The Cu2O-rGO-C3N4 photocatalyst was reused for four times without loss in its activity.

  3. Superconducting and normal state properties of niobium-potasium chloride composites

    International Nuclear Information System (INIS)

    Boysel, R.M.

    1981-01-01

    The electrical resistivity, current-voltage characteristics, critical currents, and DC magnetic susceptibility of composites consisting of 50 μm grains of Nb randomly dispersed in a KCl medium were measured. Data were taken between 1.2K and 20K in magnetic fields from 0 to +- 5G. The resistivity and current-voltage characteristics were measured using a standard four-terminal AC technique with a voltage sensitivity of 1 to 2nV, and the magnetic susceptibility was measured using an rf SQUID magnetometer. We found that samples with rho/sub n/ 2 . For 0.1Ω-cm 10Ω-cm there was no superconducting transition. The susceptibility decreased slowly below the grain transition temperature T/sub infinity/ and even below T/sub c/ in samples which underwent resistive transitions. The shape of the resistive transitions and the kink structure in the I-V's require a phase coherent transition model to adequately describe them. However, the poor fit of the theory to our data, the existence of the voltage steps, and the changing susceptibility below the resistive transition indicate that sample disorder plays a more important role in the superconducting transition of composites than is currently accounted for by phase coherent transition theories

  4. Tensile damage and its influence on the critical current of Bi2223/Ag superconducting composite tape

    International Nuclear Information System (INIS)

    Ochiai, S; Nagai, T; Okuda, H; Oh, S S; Hojo, M; Tanaka, M; Sugano, M; Osamura, K

    2003-01-01

    We have studied the tensile behaviour of Bi2223 superconducting composite tapes at room temperature, and the influence of the tensile damages introduced at room temperature on the critical current I c and the n values at 77 K. In the measurement of the I c and n values, the overall composite with a gauge length 60 mm was divided into six elements with a gauge length of 10 mm in order to find the correlation of the I c and n values of the overall composite to those of the local elements which constitute the composite. From the measured stress-strain curve of the composite and the calculated residual strain of the Bi2223 filaments, the intrinsic fracture strain of Bi2223 filaments was estimated to be 0.09-0.12%. When the applied strain was lower than the onset strain of the filament damage, the original I c and n values were retained both in the overall composite and the elements. In this situation, while the overall voltage at the transition from superconductivity to normal conductivity of the composite was the sum of the voltages of the constituent elements, among all elements the overall voltage was affected more by the element with the lower I c (higher voltage). The damage of the filaments arose first locally, resulting in a reduction of the I c and n values in the corresponding local element, even though the other elements retained the original I c and n values. In this situation, the voltage of the overall composite stemmed dominantly from that of the firstly damaged weakest element, and the overall I c and n values were almost determined by the values of such an element. After the local element was fully damaged, the damage arose also in other elements, resulting in segmentation of the filaments. Thus, the I c and n values were reduced in all elements. The correlation of I c between the overall composite and the elements could be described comprehensively for non-damaged and damaged states from the voltage-current relation

  5. Metallurgy, fabrication, and superconducting properties of multifilamentary Nb3Al composites

    International Nuclear Information System (INIS)

    Hafstrom, J.W.

    1976-01-01

    The control of metallurgical structure during fabrication that will improve the superconducting properties of multifilamentary, aluminium-stabilized, Nb 3 Al composites is described. Composites are fabricated by placing niobium rods in an aluminum matrix, and then drawing to wire. Nb 3 Al is formed at temperatures exceeding 1800 0 C for about 5 s and ordered at 750 0 C for 48 h. A critical current, J/sub c/(H), in excess of 10 5 A/cm 2 (F/sub p/ approximately equal to 7 x 10 8 dynes/cm 3 ) at 7 T and a T/sub c/ to 18.2 K are obtained. Attempts to improve J/sub c/(H) by controlling the grain size in the Nb 3 Al diffused layer are discussed. Precipitates, arising from the addition of carbon during Nb 3 Al layer growth, do not appear to be effective as grain-boundary or flux pinners. When 1 percent Zr is added to the Nb, the growth of the Nb 3 Al layer is accelerated, T/sub c/ is lowered and J/sub c/(H) is not significantly improved. J/sub c/(H) rapidly decreases with an increase in Nb 3 Al or (Nb-Zr) 3 Al layer thickness, d. J/sub c/(H) is independent of d in composites with d greater than or approximately equal to 1.5 μm. In general, the Nb 3 Al grain size appears comparable to d for d less than or equal to 1 μm. Significant improvement of J/sub c/(H) for Nb 3 Al superconducting composites reacted at temperatures above 1800 0 C (to achieve T/sub c/ greater than 17 K) is achieved only by maintaining the layer thickness well below d approximately equal to 1.0 μm

  6. Superconductivity and thermal property of MgB2/aluminum matrix composite materials fabricated by 3-dimensional penetration casting method

    International Nuclear Information System (INIS)

    Matsuda, Kenji; Saeki, Tomoaki; Nishimura, Katsuhiko; Ikeno, Susumu; Mori, Katsunori; Yabumoto, Yukinobu

    2006-01-01

    Superconductive MgB 2 /Al composite material with low and high volume fractions of particles were fabricated by our special pre-packing technique and 3-dimensional penetration casting method. The composite material showed homogeneous distribution of MgB 2 particles in the Al-matrix with neither any aggregation of particles nor defects such as cracks or cavities. The critical temperature of superconducting transition (T C ) was determined by electrical resistivity and magnetization to be about 37-39 K. Specific heat measurements further supported these T C findings. The Meissner effect was also verified in the liquid He, in which a piece of the composite floated above a permanent magnet. The thermal conductivity of the MgB 2 /Al composite material was about 25 W/K·m at 30K, a value much higher than those found for NbTi or Nb 3 Sn superconducting wires normally used in practice, which are 0.5 and 0.2 W/K·m at 10 K, respectively. A billet of the superconducting material was successfully hot-extruded, forming a rod. The same as the billet sample, the rod showed an onset T C of electrical resistivity of 39 K. (author)

  7. Development of Industrially Produced Composite Quench Heaters for the LHC Superconducting Lattice Magnets

    CERN Document Server

    Szeless, Balázs; Calvone, F

    1996-01-01

    The quench heaters are vital elements for the protection of the LHC superconducting lattice magnets in the case of resistive transitions of the conductor. The basic concept of magnet protection and technical solutions are briefly presented. The quench heater consists of partially copper clad stainless steel strips sandwiched in between electric insulating carrier foils with electrical and mechanical properties such as to withstand high voltages, low temperatures, pressures and ionizing radiation. Testing of some commercial available electric insulation foils, polyimide (PI), polyetheretherketon (PEEK) and polyarylate (PA) and combinations of adhesive systems which are suitable for industrial processing are described. Possible industrial methods for series production for some 80 km of these composite quench heaters are indicated.

  8. Flux creep in Bi2Sr2CaCu2O8 epitaxial films

    International Nuclear Information System (INIS)

    Zeldov, E.; Amer, N.M.; Koren, G.; Gupta, A.

    1990-01-01

    We incorporate the experimentally deduced flux line potential well structure into the flux creep model. Application of this approach to the resistive transition in Bi 2 Sr 2 CaCu 2 O 8 epitaxial films explains the power law voltage-current characteristics and the nonlinear current dependence of the activation energy. The results cannot be accounted for by a transition into a superconducting vortex-glass phase

  9. Development of microstructure and superconductivity of silver-clad Bi(2223) composite tapes in the process of heat treatment

    International Nuclear Information System (INIS)

    Guo, Y.C.; Liu, H.K.; Dou, S.X.

    1994-01-01

    A systematic study on the development of phase composition, microstructure and superconducting properties (critical temperature Tc and critical current density J c ) in silver-clad (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10 composite tapes during the process of heat treatment has been conducted using X-ray diffraction, scanning electron microscopy and electrical measurements. The correlation between the tape's high Tc phase purity, microstructure and superconducting properties at different heat treatment stages has been carefully analysed and explained. The results indicate that pure high Tc phase, high degree of grain alignment, high mass density and good connection between grains are all essential for superconducting tapes to carry a large current. With the optimized process parameters, a critical current density J c up to 32665 A cm -2 (corresponding critical current, 42.3 A) at 77 K and self-magnetic field for silver-clad (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10 superconducting composite tapes has been achieved. (orig.)

  10. Structural and elemental characterization of high efficiency Cu2ZnSnS4 solar cells

    Science.gov (United States)

    Wang, Kejia; Shin, Byungha; Reuter, Kathleen B.; Todorov, Teodor; Mitzi, David B.; Guha, Supratik

    2011-01-01

    We have carried out detailed microstructural studies of phase separation and grain boundary composition in Cu2ZnSnS4 based solar cells. The absorber layer was fabricated by thermal evaporation followed by post high temperature annealing on hot plate. We show that inter-reactions between the bottom molybdenum and the Cu2ZnSnS4, besides triggering the formation of interfacial MoSx, results in the out-diffusion of Cu from the Cu2ZnSnS4 layer. Phase separation of Cu2ZnSnS4 into ZnS and a Cu-Sn-S compound is observed at the molybdenum-Cu2ZnSnS4 interface, perhaps as a result of the compositional out-diffusion. Additionally, grain boundaries within the thermally evaporated absorber layer are found to be either Cu-rich or at the expected bulk composition. Such interfacial compound formation and grain boundary chemistry likely contributes to the lower than expected open circuit voltages observed for the Cu2ZnSnS4 devices.

  11. The critical state stability in textured Bi2Sr2CaCu2O8+δ superconductor

    International Nuclear Information System (INIS)

    Nabialek, A.; Niewczas, M.

    2006-01-01

    The influence of parameters such as temperature, density of the critical current j c , sample dimensions and heat exchange conditions on the critical state stability has been studied in thin samples of textured Bi 2 Sr 2 CaCu 2 O 8+δ (BSCCO) superconductor, in an external magnetic field perpendicular to the wide surface of the samples. The results show that stability of the superconductor against flux jumps increases with decreasing sample thickness. A composite-like sample consisting of two superconducting slabs glued together exhibits critical state stability as a bulk sample of the same thickness while it is less stable against flux jumping than the unit slab. The field of the first flux jump H fj1 decreases with increasing magnetic field sweep rate. For a given temperature there exists a critical sweep rate below which flux jumps vanish. These observations are interpreted in terms of the current distribution in thin superconducting samples characterized by a strong demagnetizing factor. The results are compared with a model developed for samples characterized by negligible demagnetizing effects. The critical state stability in BSCCO has been discussed in terms of the diffusion of heat and of the magnetic flux within the superconductor and the influence of heat exchange on these conditions

  12. Thermodynamic analysis of the Cu2S-Cu2Te system using dissociation pressure data

    International Nuclear Information System (INIS)

    Glazov, V.M.; Pashinkin, A.S.; Burkhanov, A.S.; Saleeva, N.M.

    1978-01-01

    The Knudsen effusive method has been used for studying the dissociation pressure in the Cu 2 S-Cu 2 Te system, and on the basis of the experimental data obtained, the tellurium activity in the system and the mixing energy have been calculated. The dissociation pressure of pure components and alloys containing 10, 30, 50, 70, and 90 mol% of copper telluride within the temperature range of 750-1200 deg C has been studied. A smooth character of the concentration dependence of tellurium activity is observed, which points to the formation of a continuous series of solid solutions in the Cu 2 S-Cu 2 Te system within the temperature range studied. The data on the mixing energy in the system show a good agreement of the values obtained from the dissociation pressure with those determined from the fusibility diagram. The results indicate that the system in question is described well within the framework of the model of regular solutions

  13. Pulsed field magnetization strategies and the field poles composition in a bulk-type superconducting motor

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhen, E-mail: zhen.huang@sjtu.edu.cn [Academy of Information Technology and Electrical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Ruiz, H.S., E-mail: dr.harold.ruiz@le.ac.uk [Department of Engineering, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Coombs, T.A., E-mail: tac1000@cam.ac.uk [Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom)

    2017-03-15

    Highlights: • Different compositions of the magnetic poles have been obtained depending on the relative orientation of the magnetizing coil and the surfaces of the columns of bulks that conform a magnetic pole. • Two bidimensional models accounting for the electromagnetic response of the top and lateral cross sections of three columns of HTS bulks subjected to multiple pulsed magnetic fields have been created. • An extended PFM strategy has been proposed by considering the magnetization of at least three successive columns of HTS bulks per pole. In the extended PFM strategy the area of each one of the poles can be seen increased by a factor of 200%-400% - Abstract: High temperature superconducting (HTS) bulks offer the potential of trapping and maintaining much higher magnetic loading level compared with the conventional permanent magnets used in rotary machines, although the effective magnetization of multiple HTS bulks with different relative orientations over the surface of cylindrical rotors creates new challenges. In this paper, we present the design and numerical validation of the Pulse Field Magnetization (PFM) strategy considered for the magnetization of the four-pole synchronous fully superconducting motor developed at the University of Cambridge. In a first instance, singular columns of up to five HTS bulks aligned over the height of the rotor were subjected to up to three magnetic pulses of 1.5 T peak, and the experimental results have been simulated by considering the electrical and thermal properties of the system in a 2D approach. The entire active surface of the rotor is covered by HTS bulks of approximately the same dimensions, resulting in an uneven distribution of pole areas with at least one of the poles formed by up to 3 columns of magnetized bulks, with relatively the same peaks of trapped magnetic field. Thus, in order to effectively use the entire area of the superconducting rotor, multiple pulsed fields per column have been applied

  14. Pulsed field magnetization strategies and the field poles composition in a bulk-type superconducting motor

    International Nuclear Information System (INIS)

    Huang, Zhen; Ruiz, H.S.; Coombs, T.A.

    2017-01-01

    Highlights: • Different compositions of the magnetic poles have been obtained depending on the relative orientation of the magnetizing coil and the surfaces of the columns of bulks that conform a magnetic pole. • Two bidimensional models accounting for the electromagnetic response of the top and lateral cross sections of three columns of HTS bulks subjected to multiple pulsed magnetic fields have been created. • An extended PFM strategy has been proposed by considering the magnetization of at least three successive columns of HTS bulks per pole. In the extended PFM strategy the area of each one of the poles can be seen increased by a factor of 200%-400% - Abstract: High temperature superconducting (HTS) bulks offer the potential of trapping and maintaining much higher magnetic loading level compared with the conventional permanent magnets used in rotary machines, although the effective magnetization of multiple HTS bulks with different relative orientations over the surface of cylindrical rotors creates new challenges. In this paper, we present the design and numerical validation of the Pulse Field Magnetization (PFM) strategy considered for the magnetization of the four-pole synchronous fully superconducting motor developed at the University of Cambridge. In a first instance, singular columns of up to five HTS bulks aligned over the height of the rotor were subjected to up to three magnetic pulses of 1.5 T peak, and the experimental results have been simulated by considering the electrical and thermal properties of the system in a 2D approach. The entire active surface of the rotor is covered by HTS bulks of approximately the same dimensions, resulting in an uneven distribution of pole areas with at least one of the poles formed by up to 3 columns of magnetized bulks, with relatively the same peaks of trapped magnetic field. Thus, in order to effectively use the entire area of the superconducting rotor, multiple pulsed fields per column have been applied

  15. Studies on Bi-Sr-Ca-Cu-O glasses and superconducting glass ceramics

    International Nuclear Information System (INIS)

    Singh, R.; Zacharias, E.

    1991-01-01

    Bi-Sr-Ca-Cu-O glasses and glass ceramics of various compositions were synthesised. The glass transition temperature varies from 396 to 422degC depending on the glass composition. The bulk glass ceramics of 4334, 4336, 2223 and 4246 compositions show superconductivity when the corresponding glass samples were heat-treated in air at 820degC for 3, 9, 12 and 24 h respectively. X-ray diffraction studies show that the superconducting phase present in all these compositions is Bi 2 Sr 2 Ca 1 Cu 2 O x . The 4334 glass ceramic is almost a single-phase material with a preferred orientation such that the c axis is normal to the sample surface. The 2223 glass ceramic has a higher T c (onset) than the other three compositions indicating the presence of high T c phase (110 K) also. ESR studies on the glass samples indicate the existence of Cu 2+ . The effect of heat treatment on ESR shows that the intensity of resonance decreases with increase in heat-treatment duration. This effect is more pronounced for the 4334 and 2223 compositions. The advantages of synthesizing superconducting materials by glass route are discussed in view of practical applications. (author). 9 refs., 6 figs

  16. Advances in high-field superconducting composites by addition of artificial pinning centres to niobium-titanium

    International Nuclear Information System (INIS)

    Cooley, L.D.; Motowidlo, L.R.

    1999-01-01

    Artificial pinning-centre (APC) niobium-titanium composites attain critical current density J c values higher than 4000 A mm -2 at 5 T, 4.2 K, surpassing the barrier reached by the conventional Nb-Ti composite process. At 2 T APC composites achieve more than double the J c of conventional composites, making them particularly well suited for low-field applications. On the other hand, APC composites are inferior to conventional composites at 8 T, due to weak high-field pinning and reduced upper critical field. This review discusses fabrication techniques, microstructural development and superconducting and flux-pinning properties of APC composites. Key elements and underlying issues for achieving higher J c are identified and discussed in terms of the current state of the art. (author)

  17. GLAG theory for superconducting property variations with A15 composition in Nb3Sn wires.

    Science.gov (United States)

    Li, Yingxu; Gao, Yuanwen

    2017-04-25

    We present a model for the variation of the upper critical field H c2 with Sn content in A15-type Nb-Sn wires, within the Ginzburg-Landau-Abrikosov-Gor'kov (GLAG) theory frame. H c2 at the vicinity of the critical temperature T c is related quantitatively to the electrical resistivity ρ, specific heat capacity coefficient γ and T c . H c2 versus tin content is theoretically formulated within the GLAG theory, and generally reproduces the experiment results. As Sn content gradually approaches the stoichiometry, A15-type Nb-Sn undergoes a transition from the dirty limit to clean limit, split by the phase transformation boundary. The H-T phase boundary and pinning force show different behaviors in the cubic and tetragonal phase. We dipict the dependence of the composition gradient on the superconducting properties variation in the A15 layer, as well as the curved tail at vicinity of H c2 in the Kramer plot of the Nb 3 Sn wire. This helps understanding of the inhomogeneous-composition inducing discrepancy between the results by the state-of-art scaling laws and experiments.

  18. Raman spectra, microstructure and superconducting properties of Sb(III)-YBCO composite superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Elsabawy, Khaled M. [Chemistry Department, Faculty of Science, Tanta University, Tanta (Egypt)]. E-mail: ksabawy@yahoo.com

    2005-11-15

    The pure YBCO (YBa{sub 2}Cu{sub 3}O{sub 7}) and its variant antimony containing composites with general formula; Y{sub 1+x}Sb {sub x}Ba{sub 2}Cu{sub 3}O {sub z}, where x = 0.1, 0.2, 0.4 and 0.6 mol%, respectively, were prepared by the solid-state reaction route. X-ray measurements indicated that Sb{sup 3+} ions have a negligible effect on the main crystalline structure and substitutes Y-sites successfully in lattice structure of 123-YBCO at low concentrations of doping (x = 0.1 {sup {yields}} 0.2). From SE-microscopy mapping and EDX elemental analysis, Sb{sup 3+} was detected qualitatively with good approximation to the actual molar ratio but not observed at 123-YBCO grain boundaries which confirm that antimony (III) has diffused regularly into material bulk of superconducting 123-YBCO-phase at low concentrations. Additions of Sb(III) affected sharply on the main vibrating modes of YBCO regime particularly, on the apical oxygen (O{sub 4}) vibrational mode A {sub 1g}. Magnetic susceptibility measurements proved that antimony oxide additions have slight effect on the transport properties of YBCO-composites regime.

  19. The Cu2ZnSnSe4 thin films solar cells synthesized by electrodeposition route

    Science.gov (United States)

    Li, Ji; Ma, Tuteng; Wei, Ming; Liu, Weifeng; Jiang, Guoshun; Zhu, Changfei

    2012-06-01

    An electrodeposition route for preparing Cu2ZnSnSe4 thin films for thin film solar cell absorber layers is demonstrated. The Cu2ZnSnSe4 thin films are prepared by co-electrodeposition Cu-Zn-Sn metallic precursor and subsequently annealing in element selenium atmosphere. The structure, composition and optical properties of the films were investigated by X-ray diffraction (XRD), Raman spectrometry, energy dispersive spectrometry (EDS) and UV-VIS absorption spectroscopy. The Cu2ZnSnSe4 thin film with high crystalline quality was obtained, the band gap and absorption coefficient were 1.0 eV and 10-4 cm-1, which is quite suitable for solar cells fabrication. A solar cell with the structure of ZnO:Al/i-ZnO/CdS/Cu2ZnSnSe4/Mo/glass was fabricated and achieved an conversion efficiency of 1.7%.

  20. Relative Humidity Sensing Properties Of Cu2O Doped ZnO Nanocomposite

    International Nuclear Information System (INIS)

    Pandey, N. K.; Tiwari, K.; Tripathi, A.; Roy, A.; Rai, A.; Awasthi, P.

    2009-01-01

    In this paper we report application of Cu 2 O doped ZnO composite prepared by solid state reaction route as humidity sensor. Pellet samples of ZnO-Cu 2 O nanocrystalline powders with 2, 5 and 10 weight% of Cu 2 O in ZnO have been prepared. Pellets have been annealed at temperatures of 200-500 deg. C and exposed to humidity. It is observed that as relative humidity increases, resistance of the pellet decreases for the humidity from 10% to 90%. Sample with 5% of Cu 2 O doped in ZnO and annealed at 500 deg. C shows best results with sensitivity of 1.50 MΩ/%RH. In this case the hysteresis is low and the reproducibility high, making it the suitable candidate for humidity sensing.

  1. Advanced composite materials and processes for the manufacture of SSC (Superconducting Super Collider) and RHIC (Relativistic Heavy Ion Collider) superconducting magnets used at cryogenic temperatures in a high radiation environment

    Energy Technology Data Exchange (ETDEWEB)

    Sondericker, J.H.

    1989-01-01

    Presently, BNL work on superconducting magnets centers mainly on the development of 17 meter length dipoles for the Superconducting Super Collider Project, approved for construction at Waxahatchie, Texas and 9.7 meter dipoles and quadrupoles for the Relativistic Heavy Ion Collider, a BNL project to start construction next year. This paper will discuss the role of composites in the manufacture of magnets, their operational requirements in cryogenic and radiation environments, and the benefits derived from their use. 13 figs.

  2. Advanced composite materials and processes for the manufacture of SSC [Superconducting Super Collider] and RHIC [Relativistic Heavy Ion Collider] superconducting magnets used at cryogenic temperatures in a high radiation environment

    International Nuclear Information System (INIS)

    Sondericker, J.H.

    1989-01-01

    Presently, BNL work on superconducting magnets centers mainly on the development of 17 meter length dipoles for the Superconducting Super Collider Project, approved for construction at Waxahatchie, Texas and 9.7 meter dipoles and quadrupoles for the Relativistic Heavy Ion Collider, a BNL project to start construction next year. This paper will discuss the role of composites in the manufacture of magnets, their operational requirements in cryogenic and radiation environments, and the benefits derived from their use. 13 figs

  3. High-temperature electrical properties of the Bi2.1Sr1.9(Ca1-xYx)Cu2Oy solid solution

    International Nuclear Information System (INIS)

    Hong, Byungsun; Mason, T.O.

    1993-01-01

    By a combination of conventional physical property measurements and high temperature electrical property studies, the solid solution limit, transport parameters, and potential defect regimes of the Bi 2.1 Sr 1.9 (Ca 1 - x Y x )Cu 2 O y solid solution were established. A continuous solid solution extends to x = 0.7 or 0.8. The electrical properties indicate that the product of the hole density-of-states and mobility for semiconducting compositions is approximately an order of magnitude smaller than for the other p-type superconducting cuprates. A pronounced drop in hole concentration accompanies the tetragonal-to-orthorhombic transition at x = 0.5, where after superconductivity disappears. The electrical properties also indicate that a composition x ≥ 0.7 is the appropriate ''reference'' compound for the solid solution series. Upon doping this yttrium-rich insulating composition with calcium, holes are introduced. With increased calcium content (decreased yttrium content) the system exhibits several defect regimes reminiscent of the behavior in the La 2 - x AE x CuO 4 (AE = Sr or Ba) system. Oxygen defects (interstitial and vacancies) are believed to play an important role in the defect structure

  4. ac superconducting articles

    International Nuclear Information System (INIS)

    Meyerhoff, R.W.

    1977-01-01

    A noval ac superconducting cable is described. It consists of a composite structure having a superconducting surface along with a high thermally conductive material wherein the superconducting surface has the desired physical properties, geometrical shape and surface finish produced by the steps of depositing a superconducting layer upon a substrate having a predetermined surface finish and shape which conforms to that of the desired superconducting article, depositing a supporting layer of material on the superconducting layer and removing the substrate, the surface of the superconductor being a replica of the substrate surface

  5. Chemical synthesis of Cu2Se nanoparticles at room temperature

    International Nuclear Information System (INIS)

    Rong, Fengxia; Bai, Yan; Chen, Tianfeng; Zheng, Wenjie

    2012-01-01

    Graphical abstract: The Cu 2 Se nanoparticles were synthesized by a simple and rapid method at room temperature. The TEM and SEM images show that the Cu 2 Se nanoparticles were spherical. Highlights: ► Cu 2 Se nanoparticles were synthesized by the reaction of nanoSe 0 sol with Cu + ions. ► The Cu 2 Se nanoparticles were spherical with cubic structure and well crystallized. ► Optical and electrochemical properties of Cu 2 Se nanoparticles were observed. ► The formation mechanism of Cu 2 Se nanoparticles was proposed. -- Abstract: A simple and rapid method has been developed to synthesize cuprous selenide (Cu 2 Se) nanoparticles by the reaction of selenium nanoparticles sol with copper sulfate solution containing ascorbic acid at room temperature. Cu 2 Se nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy dispersive X-ray analysis (EDX). The results indicated that Cu 2 Se nanoparticles were cubic crystal structure and spherical with the diameter about 75 nm. The ultraviolet–visible absorption spectrum (UV–vis) and cyclic voltammetry of Cu 2 Se nanoparticles were also investigated. The optical band gap energy of Cu 2 Se nanoparticles was 1.94 eV. On the basis of a series of experiments and characterizations, the formation mechanism of Cu 2 Se nanoparticles was discussed.

  6. Hole-doping effects on the magnetic properties of the La4Ba2Cu2O10 ferromagnet

    International Nuclear Information System (INIS)

    Mizuno, F.; Masuda, H.; Hirabayashi, I.; Tanaka, S.; Mochiku, T.; Asano, H.; Izumi, F.

    1992-01-01

    Hole-doping effects by Ba substitution for La in La 4-x Ba 2+x Cu 2 O 10 (0 ≤ x ≤ 1) have been studied to explore the possibilities of its metal-insulator transition and superconductivity. We have not detected any symptoms for metal-insulator transition, but found certain evidence for the hole-doping effect. We observed the dilution effect of Cu 2+ spin by non-magnetic Cu 3+ on the ferromagnetic transition temperature and the reduction of effective magnetic moment. (orig.)

  7. Synthesis of Cu2O, CuCl, and Cu2OCl2 nanoparticles by ultrafast ...

    Indian Academy of Sciences (India)

    2014-02-13

    Feb 13, 2014 ... 800 nm and ∼2 ps laser pulses. Cu2O NPs exhibited two-photon absorption at lower peak intensities while three-photon absorption was observed at higher peak intensities. Other samples exhibited two-photon absorption at all peak intensities. Keywords. Picosecond; laser ablation; copper complex; ...

  8. Synthesis of Cu 2 O, CuCl, and Cu2OCl 2 nanoparticles by ultrafast ...

    Indian Academy of Sciences (India)

    2014-02-13

    Feb 13, 2014 ... We have also performed nonlinear optical studies of colloidal nanoparticles using Z-scan technique at 800 nm and ∼2 ps laser pulses. Cu2O NPs exhibited two-photon absorption at lower peak intensities while three-photon absorption was observed at higher peak intensities. Other samples exhibited ...

  9. Direct measurement of elastic modulus of Nb 3Sn using extracted filaments from superconducting composite wire and resin impregnation method

    Science.gov (United States)

    Hojo, M.; Matsuoka, T.; Hashimoto, M.; Tanaka, M.; Sugano, M.; Ochiai, S.; Miyashita, K.

    2006-10-01

    Young's modulus of Nb3Sn filaments in Nb3Sn/Cu superconducting composite wire was investigated in detail. Nb3Sn filaments were first extracted from composite wire. Nitric acid and hydrofluoric acid were used to remove copper stabilizer, Nb3Sn/Nb barrier and bronze. Then, Nb3Sn filaments were impregnated with epoxy resin to form simple filament bundle composite rods. A large difference in Young's moduli of filaments and epoxy resin enhance the accuracy of the measurement of Nb3Sn filament modulus. The ratio of Nb3Sn to Nb in filaments and the number of filaments in the fiber bundle composite rods were used in the final calculation of the Young's modulus of Nb3Sn. The obtained modulus of 127 GPa was the lower bound of the already reported values.

  10. Direct measurement of elastic modulus of Nb3Sn using extracted filaments from superconducting composite wire and resin impregnation method

    International Nuclear Information System (INIS)

    Hojo, M.; Matsuoka, T.; Hashimoto, M.; Tanaka, M.; Sugano, M.; Ochiai, S.; Miyashita, K.

    2006-01-01

    Young's modulus of Nb 3 Sn filaments in Nb 3 Sn/Cu superconducting composite wire was investigated in detail. Nb 3 Sn filaments were first extracted from composite wire. Nitric acid and hydrofluoric acid were used to remove copper stabilizer, Nb 3 Sn/Nb barrier and bronze. Then, Nb 3 Sn filaments were impregnated with epoxy resin to form simple filament bundle composite rods. A large difference in Young's moduli of filaments and epoxy resin enhance the accuracy of the measurement of Nb 3 Sn filament modulus. The ratio of Nb 3 Sn to Nb in filaments and the number of filaments in the fiber bundle composite rods were used in the final calculation of the Young's modulus of Nb 3 Sn. The obtained modulus of 127 GPa was the lower bound of the already reported values

  11. Contributions to the study of superconducting multifilamentary composites and cables; Contributions a l`etude du comportement des composites et cables supraconducteurs

    Energy Technology Data Exchange (ETDEWEB)

    Turck, B

    1992-03-01

    This report is a collection of published papers in French and in English on superconducting composites and cables. All domains concerning the behaviour of superconductors in coils for field generation have been covered: critical current, current distribution, instabilities, losses in varying field. This document provides with expressions and criteria for conductor design, with conditions for achieving given performances and with criteria for design and optimization of structures of multifilamentary composites and cables. These publications have played a determining role in the understanding of the behaviour of superconductors and in their use in high performing magnets.

  12. Cu2+ in layered compounds: origin of the compressed geometry in the model system K2ZnF4:Cu2+.

    Science.gov (United States)

    Aramburu, J A; García-Lastra, J M; García-Fernández, P; Barriuso, M T; Moreno, M

    2013-06-17

    Many relevant properties (including superconductivity and colossal magnetoresistance) of layered materials containing Cu(2+), Ag(2+), or Mn(3+) ions are commonly related to the Jahn-Teller instability. Along this line, the properties of the CuF6(4-) complex in the K2ZnF4 layered perovskite have recently been analyzed using a parametrized Jahn-Teller model with an imposed strain [Reinen, D. Inorg. Chem.2012, 51, 4458]. Here, we present results of ab initio periodic supercell and cluster calculations on K2ZnF4:Cu(2+), showing unequivocally that the actual origin of the unusual compressed geometry of the CuF6(4-) complex along the crystal c axis in that tetragonal lattice is due to the presence of an electric field due to the crystal surrounding the impurity. Our calculations closely reproduce the experimental optical spectrum. The calculated values of the equilibrium equatorial and axial Cu(2+)-F(-) distances are, respectively, R(ax) = 193 pm and R(eq) = 204 pm, and so the calculated distortion R(ax) - R(eq) = 11 pm is three times smaller than the estimated through the parametrized Jahn-Teller model. As a salient feature, we find that if the CuF6(4-) complex would assume a perfect octahedral geometry (R(ax) = R(eq) = 203 pm) the antibonding a(1g)*(∼3z(2) - r(2)) orbital is placed above b(1g)*(∼x(2) - y(2)) with a transition energy E((2)A(1g) → (2)B(1g)) = 0.34 eV. This surprising fact stresses that about half the experimental value E((2)A(1g) → (2)B(1g)) = 0.70 eV is not due to the small shortening of the axial Cu(2+)-F(-) distance, but it comes from the electric field, E(R)(r), created by the rest of the lattice ions on the CuF6(4-) complex. This internal field, displaying tetragonal symmetry, is thus responsible for the compressed geometry in K2ZnF4:Cu(2+) and the lack of symmetry breaking behind the ligand relaxation. Moreover, we show that the electronic energy gain in this process comes from bonding orbitals and not from antibonding ones. The present

  13. Electronic Raman scattering in Bi2Sr2CaCu2O8=δ

    International Nuclear Information System (INIS)

    Quilty, J.W.; Trodahl, H.J.; Pooke, D.

    1996-01-01

    Full text: High-T c superconductors exhibit a definite Electronic Raman Scattering (ERS) continuum, which most materials do not. Typically, the continuum is relatively flat in the normal state, while below T c the ERS spectrum shows reduced scattering at the lowest Raman shifts and a peak close to the superconducting gap energy. The behaviour below T c is due to the breaking of Cooper pairs and reflects the superconducting density of states, hence revealing the superconducting gap. Through an appropriate choice of incident and scattered polarisation vectors, the electronic Raman continuum of high-T c superconductors may also be used to reveal information on the symmetry of the superconducting gap. Previous studies of the electronic continuum show that a broad peak associated with the superconducting gap forms in the continuum below T c in these materials, when compared to the normal-state. We report temperature and polarisation dependent ERS measurements on differently-doped Bi 2 Sr 2 CaCu 2 O 8+δ (Bi2212) single crystals, within a temperature range of 300 K to 10 K

  14. Morphology of growth of Bi2Sr2CaCu2O8 single crystals

    Science.gov (United States)

    Indenbom, M. V.; van der Beek, C. J.; Berseth, V.; Wolf, Th.; Berger, H.; Benoit, W.

    1996-12-01

    A good correlation of twins on the basal surface of flux-grown Bi2Sr2CaCu2Ox (BSCCO) single crystals with surface. growth steps is observed, the b-axis being perpendicular to the steps and, thus, parallel to the growth direction. It is found that mono-twin BSCCO single crystals produced by the travelling solvent floating zone method also grow preferentially along b, i.e. nearly perpendicularly to the boule axis, contrary to the common belief. This new understanding of the morphology of growth explains the nature of major defects in these crystals, which considerably change their measured superconducting properties, in a different way.

  15. Phase controlled solvothermal synthesis of Cu_2ZnSnS_4, Cu_2ZnSn(S,Se)_4 and Cu_2ZnSnSe_4 Nanocrystals: The effect of Se and S sources on phase purity

    International Nuclear Information System (INIS)

    Pal, Mou; Mathews, N.R.; Paraguay-Delgado, F.; Mathew, X.

    2015-01-01

    In this study, we have reported the synthesis of Cu_2ZnSnSe_4 (CZTSe), Cu_2ZnSnS_4 (CZTS) and Cu_2ZnSn(S,Se)_4 (CZTSSe) nanocrystals with tunable band gap and composition obtained by solvothermal method. The crystalline structure, composition, morphology and optical properties of the nanoparticles were characterized by X-ray diffraction (XRD), Raman scattering, energy dispersive X-ray spectroscopy, transmission electron microscopy and diffuse reflectance (DR) spectroscopy. While the XRD patterns of CZTS and CZTSe nanoparticles prepared with elemental S/Se powder revealed the presence of phase pure nanoparticles, the CZTSSe nanoparticles obtained using a mixture of S and Se, were found to contain many secondary phases under the same synthesis protocol. Formation of impurity phases in CZTSSe sample, can be avoided by using a mixture of 1-dodecanethiol (DT; CH_3(CH_2)_1_1SH)/oleylamine (OLA) instead of S powder and following the same experimental procedure. The incorporation of S in CZTSe nanocrystals prepared in presence of DDT/OLA mixture was confirmed through structural and optical characterizations. The optical properties of the quaternary chalcogenide nanocrystals were found to vary with the chemical composition of the material. - Highlights: • Solvothermal synthesis of CZTS, CZTSSe and CZTSe nanocrystals and discussion on possible formation mechanism. • Use of dodecanethiol/oleylamine mixture to synthesize phase-pure CZTSSe nanocrystals. • Formation of impurity phases can be controlled with proper S and Se sources.

  16. Property-porosity relationships for polymer-impregnated superconducting ceramic composite

    International Nuclear Information System (INIS)

    Salib, S.; Vipulanandan, C.

    1990-01-01

    A thermoplastic polymer, poly(methyl methacrylate) (PMMA), was used to improve the flexural properties of the high-temperature superconducting ceramic (YBa 2 Cu 3 O 7-δ ). Ceramic specimens with different porosities were prepared by dry compacting 12.5-mm-diameter disk specimens at various uniaxial pressures. Density-pressure relationships have been developed for before- and after-sintering conditions. The PMMA polymer was impregnated into the porous ceramic at room temperature. The mechanical properties were evaluated by concentrically loading simply supported disk specimens. The load-displacement responses were analyzed using the finite-element method. Impregnation of PMMA polymer at room temperature increased the flexural strength and modulus of the superconducting ceramic without affecting its electrical properties. The flexural properties depended on the porosity of the ceramics, and, hence, linear and nonlinear property-porosity relationships have been used to characterize the behavior of superconducting ceramic with an without the polymer

  17. Efficiency of Cu2O/BiVO4 particles prepared with a new soft procedure on the degradation of dyes under visible-light irradiation

    International Nuclear Information System (INIS)

    Aguilera-Ruiz, Eduardo; García-Pérez, Ulises M.; Garza-Galván, María de la; Zambrano-Robledo, Patricia; Bermúdez-Reyes, Bárbara

    2015-01-01

    Graphical abstract: - Highlights: • Cu 2 O/BiVO 4 p–n heterojunctions were synthesized by a simple impregnation method. • The photocatalytic performance was evaluated using a LED lamp as visible source. • The composite with 1 wt.% of Cu 2 O exhibits the best visible-light-activity. • A mechanism for the carriers transfer is proposed. • Factors as pH and O 2 were found to influence the degradation rate. - Abstract: Cu 2 O/BiVO 4 composites with different concentrations of Cu 2 O were synthesized by a simple impregnation method at 200 °C under N 2 atmosphere for 4 h. The as-synthesized samples were characterized by X-ray powder diffraction, scanning electron microscopy, UV–vis diffuse reflection absorption and vis photoluminescence. The morphology of the as-synthesized composites with different weight ratios of Cu 2 O is composed by quasi-spherical and dendrite-like particles. The photocatalytic performance of the Cu 2 O/BiVO 4 composites was evaluated by degradation of methyl orange solutions under visible-LED irradiation. The results obtained show that the photocatalytic behavior of the p–n heterojunction Cu 2 O/BiVO 4 composites was better than pure Cu 2 O and BiVO 4 . The variation of the reaction parameters, such as solution pH and presence of O 2 , improved the photocatalytic performance of Cu 2 O/BiVO 4 composite. Meanwhile, a possible mechanism for methyl orange photocatalytic degradation over Cu 2 O/BiVO 4 photocatalysts was proposed. The chemical stability and reusability of Cu 2 O/BiVO 4 powders were also investigated

  18. Growth and properties of oxygen doped Bi2Sr2CaCu2O8+δ single crystals

    International Nuclear Information System (INIS)

    Kapitulnik, A.; Mitzi, D.B.

    1990-01-01

    This paper reports results on oxygen doped single crystals in the Bi 2 Sr 2 CaCu 2 O 8+δ system grown by a directional solidification method. Annealing of as made crystals in increasing partial pressure of oxygen reversibly depresses the superconducting transition temperature from 90K (as made) to 77K (oxygen pressure annealed). Magnetic and photoemission properties of these crystals will be discussed

  19. Facile fabrication of p-n heterojunctions for Cu2O submicroparticles deposited on anatase TiO2 nanobelts

    International Nuclear Information System (INIS)

    Li, Li; Lei, Jingguo; Ji, Tianhao

    2011-01-01

    Graphical abstract: Cu 2 O particle-deposited TiO 2 nanobelts with p-n semiconductor heterojunction structure were successfully prepared via two-step preparation process, and their visible-light photodegradation activities of Rhodamine B were investigated in detail. Highlights: → Cu 2 O particle-deposited TiO 2 nanobelts mainly with diameters in a range of 200-400 nm were successfully prepared. → The amount of Cu 2 O particles deposited on TiO 2 nanobelts can be tuned. → The composite structure with Cu 2 O particles and TiO 2 nanobelts exhibits p-n semiconductor heterojunction performance. → Photocatalytic properties of such composites. -- Abstract: In this paper, Cu 2 O particle-deposited TiO 2 nanobelts with p-n semiconductor heterojunction structure were successfully prepared via a two-step preparation process to investigate electron-transfer performance between p-type Cu 2 O and n-type TiO 2 . Various measurement results confirm that the amount of pure Cu 2 O submicroparticles, with diameters within the range of 200-400 nm and deposited on the surface of TiO 2 nanobelts, can be controlled, and that the purity of Cu 2 O is heavily affected by reaction time. Visible-light photodegradation activities of Rhodamine B show that photocatalysts have little or no photocatalytic activities mainly due to their p-n heterojunction structure, indicating that there hardly appears any electron-transfer from Cu 2 O to TiO 2 .

  20. ZrCu2P2 and HfCu2P2 phosphides and their crystal structure

    International Nuclear Information System (INIS)

    Lomnitskaya, Ya.F.

    1986-01-01

    Isostructural ZrCu 2 P 2 and HfCu 2 P 2 compounds are prepared for the first time. X-ray diffraction analysis (of powder, DRON-2.0 diffractometer, FeKsub(α) radiation) was used to study crystal structure of HfCu 2 P 2 phosphide belonging to the CaAl 2 Si 2 structural type (sp. group P anti 3 m 1, R=0.095). Lattice parameters the compounds are as follows: for ZrCu 2 P 2 a=0.3810(1), c=0.6184(5); for HfCu 2 P 2 a=0.3799(1), c=0.6160(2) (nm). Atomic parameters in the HfCu 2 P 2 structure and interatomic distances are determined

  1. Growth and properties of oxygen- and ion-doped Bi2Sr2CaCu2O8+δ single crystals

    International Nuclear Information System (INIS)

    Mitzi, D.B.; Lombardo, L.W.; Kapitulnik, A.; Laderman, S.S.; Jacowitz, R.D.

    1990-01-01

    A directional solidification method for growing large single crystals in the Bi 2 Sr 2 CaCu 2 O 8+δ system is reported. Ion doping, with replacement of La for Sr and Y for Ca, as well as oxygen doping in these crystals has been explored. Doped and undoped crystals have been characterized using microprobe analysis, x-ray diffraction, thermogravimetric analysis, and magnetic and Hall measurements. Ion doping results in little change of the superconducting transition for substitution levels below 20--25%, while beyond this level the Meissner signal broadens and the low-temperature Meissner signal decreases. Microprobe analysis and x-ray diffraction performed on these more highly substituted single crystals provide evidence for inhomogeneity and phase segregation into regions of distinct composition. Annealing unsubstituted crystals in increasing partial pressures of oxygen reversibly depresses the superconducting transition temperature from 90 (as made) to 77 K (oxygen pressure annealed), while the carrier concentrations, as determined from Hall effect measurements, increase from n=3.1(3)x10 21 cm -3 (0.34 holes per Cu site) to 4.6(3)x10 21 cm -3 (0.50 holes per Cu site)

  2. Vibrational properties of stannite and kesterite type compounds: Raman scattering analysis of Cu2(Fe,Zn)SnS4

    International Nuclear Information System (INIS)

    Fontané, X.; Izquierdo-Roca, V.; Saucedo, E.; Schorr, S.; Yukhymchuk, V.O.; Valakh, M.Ya.; Pérez-Rodríguez, A.; Morante, J.R.

    2012-01-01

    Highlights: ► Analysis of main and weaker Raman peaks from Cu 2 FeZnS 4 and Cu 2 ZnSnS 4 compounds. ► Identification of a cation disorder induced Raman peak in Cu 2 ZnSnS 4 . ► Analysis of spectral features of main Raman peaks from Cu 2 (Fe,Zn)SnS 4 . - Abstract: This work reports the analysis of the vibrational properties of stannite–kesterite Cu 2 (Fe,Zn)SnS 4 compounds that has been performed by Raman scattering measurements. The detailed analysis of the experimental spectra has allowed determining the frequency and symmetry assignment of the main and weaker peaks from both stannite Cu 2 FeSnS 4 (CFTS) and kesterite Cu 2 ZnSnS 4 (CZTS) phases. The measurements performed in the kesterite CZTS samples have also revealed the presence of local inhomogeneities that are characterised by an additional peak in the spectra at about 331 cm −1 . This peak has been related to the presence in these local regions of a high degree of disorder in the cation sublattice, in agreement with previous neutron diffraction analysis in similar samples. Finally, the spectra from the solid solution alloys show a one-mode behaviour of the main A/A 1 peak with the chemical composition.

  3. Characterization and multi-scales modeling of the thermomechanical behaviour of a superconducting composite cable

    International Nuclear Information System (INIS)

    Gourdin, C.; Reytier, M.; Vedrine, P.

    2000-06-01

    The prediction of the superconducting cable mechanical properties (NbTi and Nb 3 Sn) becomes a great stake for the STCM applications. During the design phase of our magnets, the electromagnetic forces become considerable. Therefore, the control and the accuracy of the structural calculations need well known mechanical properties for each component. But, superconducting cables present, in compression, a non linear mechanical behaviour with a significant hysteresis, which will have to be taken into account in a near future. That is why a study is started in order to understand and to formulate this particular mechanical behaviour. In this paper, the NbTi and Nb 3 Sn cable structure is first presented as well as their manufacturing process. Then, a description of the experimental procedure used to realize the compression tests is made. Finally, the main results obtained at room temperature and also in liquid helium at 4.2 K are discussed. (author)

  4. Growth and properties of oxygen- and ion-doped Bi2Sr2CaCu2O8+δ single crystals

    Science.gov (United States)

    Mitzi, D. B.; Lombardo, L. W.; Kapitulnik, A.; Laderman, S. S.; Jacowitz, R. D.

    1990-04-01

    A directional solidification method for growing large single crystals in the Bi2Sr2CaCu2O8+δ system is reported. Ion doping, with replacement of La for Sr and Y for Ca, as well as oxygen doping in these crystals has been explored. Doped and undoped crystals have been characterized using microprobe analysis, x-ray diffraction, thermogravimetric analysis, and magnetic and Hall measurements. Ion doping results in little change of the superconducting transition for substitution levels below 20-25%, while beyond this level the Meissner signal broadens and the low-temperature Meissner signal decreases. Microprobe analysis and x-ray diffraction performed on these more highly substituted single crystals provide evidence for inhomogeneity and phase segregation into regions of distinct composition. Annealing unsubstituted crystals in increasing partial pressures of oxygen reversibly depresses the superconducting transition temperature from 90 (as made) to 77 K (oxygen pressure annealed), while the carrier concentrations, as determined from Hall effect measurements, increase from n=3.1(3)×1021 cm-3 (0.34 holes per Cu site) to 4.6(3)×1021 cm-3 (0.50 holes per Cu site). No degradation of the Meissner transition or other indications of inhomogeneity or phase segregation with doping are noted, suggesting that oxygen-doped Bi2Sr2CaCu2O8+δ is a suitable system for pursuing doping studies. The decrease in Tc with concentration for 0.34<=n<=0.50 indicates that a high-carrier-concentration regime exists in which Tc decreases with n and suggests that this decrease does not arise from material inhomogeneity or other materials problems. An examination of the variation of Tc with the density of states and lattice constants for all of the doped and undoped superconducting samples considered here indicates that changes in Tc with doping are primarily affected by changes in the density of states (or carrier concentration) rather than by structural variation induced by the doping.

  5. Facile preparation of polyethylenimine-tannins coated SiO2 hybrid materials for Cu2+ removal

    Science.gov (United States)

    Huang, Qiang; Liu, Meiying; Zhao, Jiao; Chen, Junyu; Zeng, Guangjian; Huang, Hongye; Tian, Jianwen; Wen, Yuanqing; Zhang, Xiaoyong; Wei, Yen

    2018-01-01

    Polyethylenimine-tannins coated SiO2 (SiO2@PEI-TA) hybrid materials have been prepared via a single-step multifunctional coating with polyethylenimine (PEI) and tannins (TA), and characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The as-prepared SiO2@PEI-TA composites were examined as adsorbents to remove the Cu2+ from aqueous solution. The effects of contact time, initial Cu2+ concentration, solution pH and temperature, on Cu2+ adsorption have been investigated. The results show that the adsorption of Cu2+ onto SiO2@PEI-TA is dependent on the contact time, Cu2+ concentration, pH and temperature. The SiO2@PEI-TA composites show a 2.4-fold increase in adsorption capacity, implying that the introduction of PEI-TA coating is in favor of the Cu2+ adsorption. Based on the analysis of kinetic data, the kinetics of Cu2+ adsorption is more accurately described by the pseudo-second-order model. The equilibrium data are analyzed by Langmuir and Freundlich isotherms. Results of isotherms show that the better agreement is Freundlich isotherm model with correlation coefficient of 0.9914, which suggests that the adsorption of Cu2+ onto SiO2@PEI-TA is mainly a heterogeneous adsorption process. Thermodynamic analyses show that the adsorption interaction is actually a spontaneous and endothermic chemical process, which might involve the chemical chelation between Cu2+ and functional groups (amine and carboxyl groups) on the surface of SiO2@PEI-TA. In addition, the Cu2+ ions could desorb from SiO2@PEI-TA by using acid solution and the adsorption efficiency remains at high level after five adsorption-desorption recycles. These results provide potential applications of these novel adsorbents for the removal of heavy metal Cu2+ from aqueous solution and also provide strong evidence to support the adsorption mechanism proposed in the study.

  6. Electrostatic assembly of Cu2O nanoparticles on DNA templates

    International Nuclear Information System (INIS)

    Wang Li; Wei Gang; Qi Bin; Zhou Hualan; Liu Zhiguo; Song Yonghai; Yang Xiurong; Li Zhuang

    2006-01-01

    In this paper, a method for highly ordered assembly of cuprous oxide (Cu 2 O) nanoparticles (NPs) by DNA templates was reported. Cetyltrimethylammonium bromide (CTAB)-capped Cu 2 O NPs were adsorbed onto well-aligned λ-DNA chains to form necklace-like one-dimensional (1D) nanostructures. UV-vis, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the nanostructure. The Cu 2 O nanostructures fabricated with the method are both highly ordered and quite straight

  7. Multifilamentary superconducting (NbTa)-Sn composite wire by solid-liquid reaction for possible application above 20 tesla

    International Nuclear Information System (INIS)

    Hong, M.; Hull, G.W. Jr.; Fuchs, E.O.; Holthuis, J.T.

    1983-01-01

    Nb alloyed with Ta was employed in fabricating multifilamentary composite wires of (NbTa)-Sn using the liquid-infiltration process. The superconducting A15 phase was formed with subsequent heat treatments at 800-950 0 C by the solid-liquid reaction. High inductive Tsub(c)'s of 18.2 K with sharp transition width ( 4 A/cm 2 at 2O T and 4.2 K were obtained. It was found that 2 wt.% Ta in the Nb was sufficient in the enhancement of the overall Jsub(c) at the high fields and in increasing the Hsub(c2) (4.2 K) to 25 T. (Auth.)

  8. Multifilamentary superconducting (NbTa)-Sn composite wire by solid-liquid reaction for possible application above 20 tesla

    International Nuclear Information System (INIS)

    Hong, M.; Hull, G.W. Jr.; Fuchs, E.O.; Holthuis, J.T.

    1983-01-01

    Nb alloyed with Ta was employed in fabricating multifilamentary composite wires of (NbTa)-Sn using the liquid-infiltration process. The superconducting A15 phase was formed with subsequent heat treatments at 800-950 0 C by the solid-liquid reaction. High inductive Tsub(c)'s of 18.2 K with sharp transition width ( 4 A/cm 2 at 20 T and 4.2 K were obtained. It was found that 2 wt.% Ta in the Nb was sufficient in the enhancement of the overall Jsub(c) at the high fields and in increasing the Hsub(c2) (4.2 K) to 25 T. (orig.)

  9. Cu_2O Hybridized Titanium Carbide with Open Conductive Frameworks for Lithium-ion Batteries

    International Nuclear Information System (INIS)

    Zhang, Huang; Dong, Hui; Zhang, Xuan; Xu, Yunlong; Fransaer, Jan

    2016-01-01

    Though MXenes, a new family of 2D transition metal carbides, are generating considerable interests as electrode materials for batteries and supercapacitors, further application is hindered by their low capacities and poor rate capabilities. Here we propose a simple route for the synthesis of Cu_2O particle hybridized titanium carbide Ti_2CT_x (T = O, OH) composites via a solvothermal method. Electrodes containing Cu_2O/MXene were fabricated without carbon black, and tested as anodes for lithium ion batteries. A discharge capacity of 143 mAh g"−"1 was obtained at a discharge current density of 1000 mA g"−"1 and the capacity retention was near 100% after 200 cycles. The hybrid electrodes with open conductive frameworks exhibited significantly improved electrochemical performance, suggesting a new method for preparing MXene-based composites for energy storage application.

  10. Superconductivity and its application

    International Nuclear Information System (INIS)

    Spadoni, M.

    1988-01-01

    This paper, after a short introduction to superconductivity and to multifilamentary superconducting composites is aiming to review the state of the art and the future perspective of some of the applications of the superconducting materials. The main interest is focussed to large scale applications like, for istance, magnets for accelerators or fusion reactors, superconducting system for NMR thomography, etc. A short paragraph is dedicated to applications for high sensitivity instrumentation. The paper is then concluded by some considerations about the potentialities of the newly discovered high critical temperature materials

  11. Toxicity Action of Cu2+ on Lemna minor%Cu2+对浮萍的毒性作用

    Institute of Scientific and Technical Information of China (English)

    王爱丽; 宋志慧; 程守敬

    2004-01-01

    Cu2+作为胁迫因子研究了Cu2+对浮萍叶片数、叶绿素含量和过氧化物酶活性的影响.结果表明,Cu2+浓度低于200μg@L-1时,能刺激浮萍生长,对浮萍叶绿素含量影响不大;Cu2+浓度再增加时会抑制浮萍的生长;当Cu2+浓度为400 μg@L-1时,会严重影响浮萍的生长,对浮萍叶绿素含量的影响十分明显.Cu2+对浮萍过氧化物酶活性的影响随Cu2+浓度的升高逐渐增加.

  12. Potential thermoelectric performance of hole-doped Cu2O

    International Nuclear Information System (INIS)

    Chen, Xin; Parker, David; Du, Mao-Hua; Singh, David J

    2013-01-01

    High thermoelectric performance in oxides requires stable conductive materials that have suitable band structures. Here we show, based on an analysis of the thermopower and related properties using first-principles calculations and Boltzmann transport theory in the relaxation time approximation, that hole-doped Cu 2 O may be such a material. We find that hole-doped Cu 2 O has a high thermopower of above 200 μV K −1 even with doping levels as high as 5.2 × 10 20 cm −3 at 500 K, mainly attributed to the heavy valence bands of Cu 2 O. This is reminiscent of the cobaltate family of high-performance oxide thermoelectrics and implies that hole-doped Cu 2 O could be an excellent thermoelectric material if suitably doped. (paper)

  13. Process for producing clad superconductive materials

    International Nuclear Information System (INIS)

    Cass, R.B.; Ott, K.C.; Peterson, D.E.

    1992-01-01

    This patent describes a process for fabricating superconducting composite wire. It comprises placing a superconductive precursor admixture capable of undergoing self propagating combustion in stoichiometric amounts sufficient to form a superconductive product within an oxygen-porous metal tube; sealing one end of the tube; igniting the superconductive precursor admixture whereby the superconductive precursor admixture endburns along the length of the admixture; and cross-section reducing the tube at a rate substantially equal to the rate of burning of the superconductive precursor admixture and at a point substantially planar with the burnfront of the superconductive precursor mixture, whereby a clad superconductive product is formed in situ

  14. Electroless deposition and electrical characterization of N- Cu 2 O ...

    African Journals Online (AJOL)

    This work describes the preparation of n-Cu2O layer by the electroless methods of boiling and immersion of copper plates in 0.001M CuSO4Electron Microscopy (SEM) have been used to characterize the oxide films deposited. XRD studies show, for the first time, that cuprous oxide (Cu2O) and cupric oxide (CuO) were ...

  15. Composite vortex ordering in superconducting films with arrays of blind holes

    International Nuclear Information System (INIS)

    Berdiyorov, G R; Milosevic, M V; Peeters, F M

    2009-01-01

    The pinning properties of a superconducting thin film with a square array of blind holes are studied using the nonlinear Ginzburg-Landau theory. Although blind holes provide a weaker pinning potential than holes (also called antidots), several novel vortex structures are predicted for different size and thickness of the blind holes. Orientational dimer and trimer vortex states as well as concentric vortex shells can nucleate in the blind holes. In addition, we predict the stabilization of giant vortices that may be located both in the pinning centers and/or at the interstitial sites, as well as the combination of giant vortices with sets of individual vortices. For large blind holes, local vortex shell structures inside the blind holes may transfer their symmetry to interstitial vortices as well. The subtle interplay of shell formation and traditional Abrikosov vortex lattices inside the blind holes is also studied for different numbers of trapped vortices.

  16. Electro-mechanical behaviors of composite superconducting strand with filament breakage

    International Nuclear Information System (INIS)

    Wang, Xu; Gao, Yuanwen; Zhou, Youhe

    2016-01-01

    Highlights: • The electromechanical behaviors of the superconducting (SC) strand are investigated. • A 3D FEM model for bending behaviors and electric properties of strand is developed. • The influence of breakage of filaments on the critical current of SC strand is calculated. • The impact of current transfer length on the electric properties of SC strand is discussed. - Abstract: The bending behaviors of superconducting strand with typical multi-filament twist configuration are investigated based on a three-dimensional finite element method (FEM) model, named as the Multi-filament twist model, of the strand. In this 3D FEM model, the impacts of initial thermal residual stress, filament-breakage and its evaluation are taken into accounts. The mechanical responses of the strand under bending load are studied with the factors taken into consideration one by one. The distribution of the damage of the filaments and its evolution and the movement of the neutral axis caused by it are studied and displayed in detail. Besides, taking the advantages of the Multi-filament twist model, the normalized critical current of the strand under bending load is also calculated based on the invariant temperature and field strain functions. In addition, the non-negligible influences of the pitch length of the filaments on both the mechanical behaviors and the normalized critical current are discussed. The stress-strain characteristics of the strand under tensile load and the normalized critical current of it under axial and bending loads resulting from the Multi-filament twist model show good agreement with the experimental data.

  17. Electro-mechanical behaviors of composite superconducting strand with filament breakage

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xu [Key Laboratory of Mechanics on Environment and Disaster in Western China, The Ministry of Education of China, Lanzhou, Gansu 730000 (China); Department of Mechanics and Engineering Science, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000 (China); Gao, Yuanwen, E-mail: ywgao@lzu.edu.cn [Key Laboratory of Mechanics on Environment and Disaster in Western China, The Ministry of Education of China, Lanzhou, Gansu 730000 (China); Department of Mechanics and Engineering Science, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000 (China); Zhou, Youhe [Key Laboratory of Mechanics on Environment and Disaster in Western China, The Ministry of Education of China, Lanzhou, Gansu 730000 (China); Department of Mechanics and Engineering Science, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000 (China)

    2016-10-15

    Highlights: • The electromechanical behaviors of the superconducting (SC) strand are investigated. • A 3D FEM model for bending behaviors and electric properties of strand is developed. • The influence of breakage of filaments on the critical current of SC strand is calculated. • The impact of current transfer length on the electric properties of SC strand is discussed. - Abstract: The bending behaviors of superconducting strand with typical multi-filament twist configuration are investigated based on a three-dimensional finite element method (FEM) model, named as the Multi-filament twist model, of the strand. In this 3D FEM model, the impacts of initial thermal residual stress, filament-breakage and its evaluation are taken into accounts. The mechanical responses of the strand under bending load are studied with the factors taken into consideration one by one. The distribution of the damage of the filaments and its evolution and the movement of the neutral axis caused by it are studied and displayed in detail. Besides, taking the advantages of the Multi-filament twist model, the normalized critical current of the strand under bending load is also calculated based on the invariant temperature and field strain functions. In addition, the non-negligible influences of the pitch length of the filaments on both the mechanical behaviors and the normalized critical current are discussed. The stress-strain characteristics of the strand under tensile load and the normalized critical current of it under axial and bending loads resulting from the Multi-filament twist model show good agreement with the experimental data.

  18. Phosphorus and Cu2+ removal by periphytic biofilm stimulated by upconversion phosphors doped with Pr3+-Li.

    Science.gov (United States)

    Zhu, Yan; Zhang, Jianhong; Zhu, Ningyuan; Tang, Jun; Liu, Junzhuo; Sun, Pengfei; Wu, Yonghong; Wong, Po Keung

    2018-01-01

    Upconversion phosphors (UCPs) can convert visible light into luminescence, such as UV, which can regulate the growth of microbes. Based on these fundamentals, the community composition of periphytic biofilms stimulated by UCPs doped with Pr 3+ -Li + was proposed to augment the removal of phosphorus (P) and copper (Cu). Results showed that the biofilms with community composition optimized by UCPs doped with Pr 3+ -Li + had high P and Cu 2+ removal rates. This was partly due to overall bacterial and algal abundance and biomass increases. The synergistic actions of algal, bacterial biomass and carbon metabolic capacity in the Pr-Li stimulated biofilms facilitated the removal of P and Cu 2+ . The results show that the stimulation of periphytic biofilms by lanthanide-doped UCPs is a promising approach for augmenting P and Cu 2+ removal. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Superconducting thallium cuprates obtained by substitution of copper for thallium in the double-thallium layer cuprate (Tl2212)

    International Nuclear Information System (INIS)

    Gopalakrishnan, J.; Shivakumara, C.; Manivannan, V.

    1994-01-01

    A new series of superconducting thallium cuprates of nominal composition, (Tl 2-x Cu x )Ba 2 CaCu 2 O 8 (0 c s in the range 110--99K. The phases are metastable, decomposing at higher temperatures (∼1,150K) to a mixture of thallium cuprates, CuO and BaCuO 2 . Significantly, x=1 member decomposes at 1,150K to mixture of Tl2223, CuO and BaCuO 2 . Chemical titrations involving oxidation of bromide ions reveals that the copper substituting for thallium in (Tl 2-x Cu x )Ba 2 CaCu 2 O 8 most likely occurs in the III oxidation state for x≤0.25 and in a mixed state (II,III) state for x>0.25

  20. Facile synthesis, enhanced field emission and photocatalytic activities of Cu2O–TiO2–ZnO ternary hetero-nanostructures

    International Nuclear Information System (INIS)

    Wang Yang; Yu Ke; Yin Haihong; Song Changqin; Zhang Zhengli; Li Shouchuan; Zhang Qingfeng; Zhao Bin; Zhang Yingfang; Zhu Ziqiang; Shi Hui

    2013-01-01

    Cu 2 O–TiO 2 –ZnO ternary nano-heteroarchitectures were designed and successfully fabricated using titanium (IV) oxideacetylacetonate (TiO(acac) 2 ) as a precursor and polyethyleneimine (PEI) as a binding agent. Field emission and photocatalytic activities of pure Cu 2 O nanopines, Cu 2 O–TiO 2 core–shell nanopines and Cu 2 O–TiO 2 –ZnO ternary composites were investigated and compared. The results revealed that the as-prepared nano-heterojunctions and nanoparticles at the surface remarkably enhanced the field emission and photocatalytic activities of pure Cu 2 O nanopines. The as-prepared nano-heterojunctions induced interfacial states and energy band differentials, which caused electron transition and the inhibition of photo-induced electron–hole pair recombination. The nanoparticles at the surface formed thousands of surface nano-protrusions and active sites for photocatalytic chemical reactions. (paper)

  1. Applied superconductivity

    CERN Document Server

    Newhouse, Vernon L

    1975-01-01

    Applied Superconductivity, Volume II, is part of a two-volume series on applied superconductivity. The first volume dealt with electronic applications and radiation detection, and contains a chapter on liquid helium refrigeration. The present volume discusses magnets, electromechanical applications, accelerators, and microwave and rf devices. The book opens with a chapter on high-field superconducting magnets, covering applications and magnet design. Subsequent chapters discuss superconductive machinery such as superconductive bearings and motors; rf superconducting devices; and future prospec

  2. Flux line patterns in Bi2Sr2Ca1Cu2Ox

    International Nuclear Information System (INIS)

    Weiss, F.; Hardy, V.; Provost, J.; Ruyter, A.; Simon, C.

    1994-01-01

    Results of the defect influence on the flux line lattice in Bi 2 Sr 2 Ca 1 Cu 2 O x single crystals are presented. These crystals, non irradiated or irradiated at GANIL with heavy ions (Pb 56+ , 6 GeV) have been decorated with Ni particles in the superconducting state using the Bitter technique. The defects involved are columnar defects. Resulting decorated flux line patterns have been characterized using scanning electron microscopy and computer image analysis. Disorder of the decorated flux line networks has been found to be strongly dependent on the defect density, which results from the irradiation. In order to characterize this disorder, a method for determining elastic energy terms in the deformation of flux line patterns has been investigated. This method can be applied if Fourier transforms of the decorated flux line patterns exhibit distinct reflections. (orig.)

  3. Compositional analysis of YBaCuO superconducting films with ion beam analysis techniques

    International Nuclear Information System (INIS)

    Jones, S.; Timmers, H.; Ophel, T.R.; Elliman, R.G.

    1999-01-01

    High-T c YBa x Cu y O 7-δ superconducting films are being developed for applications such as superconducting quantum interference devices. The carrier concentration, critical current density J c and critical temperature T c of these films depend sensitively on the oxygen content . Stoichiometry, uniformity with depth, homogeneity across the sample and film thickness are also important quantities for their characterisation. It has been shown, for example, that the stoichiometry of the metallic elements affects the growth characteristics and surface morphology of the films. With the deposit ion techniques used, reproducibility of film properties is difficult. The characterisation of YBa x Cu y O 7-δ films with ion beam analysis techniques is complex. Whereas the three metallic elements can be detected with helium beams and Rutherford Backscattering (RBS), the oxygen signal is generally obscured by that from substrate elements. It can be better detected using resonant backscattering with 3.04MeV 4 He ions or nuclear reaction analysis. Elastic Recoil Detection (ERD) with high-energetic (1MeV/amu), heavy beams (Z > 120), enables all elements to be detected and separated in a single experiment. It is well established that ion bombardment induces vacancies in the oxygen sub-lattice, driving the material to change from crystalline to amorphous, the latter phase having a reduced oxygen content. In previous heavy ion ERD measurements of YBa x Cu yO z films with 200MeV 127 I beams, the opaque films became transparent in the beam spot area, indicative of the amorphous phase. The accuracy of the oxygen measurement is therefore questionable. Indeed, using Raman spectroscopy, distortions of the crystalline structure above a fluence of 5 x 10 11 ion/cm 2 and for higher doses some signatures of a reduction in oxygen content have been observed for such beams. It appears therefore that a correct determination of the oxygen content requires either a drastic reduction in fluence or a

  4. Electrical, Structural and Mechanical Properties of Superconducting MGB2/MG Composites

    International Nuclear Information System (INIS)

    Ulucan, S.

    2004-01-01

    The brittle nature of MgB 2 does not allow this material to be used as a stand-alone material for large scale applications based on wire production. MgB 2 /Mg composites were prepared using metal matrix composite fabrication technique. To obtain composites MgB 2 and Mg powders were mixed at different weight fractions and uniaxially pressed in a cylindrical dye under the pressure of 0.5 GPa and 1.0 GPa for two hours at various temperatures. XRD, SEM and EDX techniques were used for phase identification and microstructural studies. Resistivities of the composites were measured between 20 K and room temperature. The effect of temperature on the mechanical properties of MgB 2 /Mg composites was investigated. For this purpose, compressive mechanical testing was performed to measure elastic modulus and strain at failure values of the composites. It was found that the relative weight fraction of the powders and the temperature have same considerable effect on the electrical, microstructural and the mechanical properties of the composites

  5. Electrodeposition of flake-like Cu_2O on vertically aligned two-dimensional TiO_2 nanosheet array films for enhanced photoelectrochemical properties

    International Nuclear Information System (INIS)

    Yang, Lei; Zhang, Miao; Zhu, Kerong; Lv, Jianguo; He, Gang; Sun, Zhaoqi

    2017-01-01

    Highlights: • Flake-like Cu_2O/TNS with exposed {001} facets constructed p-n heterostructure. • The TNS arrays were used as starting substrates for Cu_2O growth. • The Cu_2O/TNS prepared at −0.4 V exhibits the best photoelectrochemical property. - Abstract: A novel Cu_2O/TNS composite structure of single crystal TiO_2 nanosheet (TNS) arrays decorated with flake-like Cu_2O were synthesized by a facile hydrothermal reaction followed by the electrodeposition process. The effects of deposition potential on the microstructure, morphology, and optical property of the thin films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis spectrophotometer. When the deposition potential is higher than −0.4 V, peaks corresponding to Cu appear, meanwhile, flake-like Cu_2O become agglomerating, and transform into dense Cu_2O particles. Additionally, photoelectrochemical experiments indicate that the films deposited at −0.4 V show the lowest resistivity and highest exciton separation efficiency. This enhanced photoelectrochemical properties can be explained by synergistic effect of p-type flake-like Cu_2O and n-type TiO_2 heterojunctions combined with two-dimensional TiO_2 nanosheet with exposed highly reactive {001} facets.

  6. Investigation of mechanical behavior of copper in Nb3Sn superconducting composite wire

    International Nuclear Information System (INIS)

    Hojo, M.; Matsuoka, T.; Nakamura, M.; Tanaka, M.; Adachi, T.; Ochiai, S.; Miyashita, K.

    2004-01-01

    The mechanical properties and the thermal residual stress distribution of copper in Nb 3 Sn/Cu composite superconductor were investigated in detail. The stabilizer copper was removed from the composite wire, and the stress-strain behavior of this wire was compared with that of the original composite wire. The subtraction yielded the stress-strain curves of the copper when the Bauschinger effect was taken into account. The tensile test of the composites from which about 30% and 60% of copper was removed suggested the existence of the distribution of the thermal residual stress in the stabilizer copper. When this factor was taken into account, the analytical stress-strain curve agreed well with the experimental stress-strain curve. Thus, the stress-stain behavior of each component was fully understood

  7. Flux Creep Investigation in Bi2Sr2CaCu2O8+d High-Temperature Superconductor

    Directory of Open Access Journals (Sweden)

    G. R. Blanca

    2004-12-01

    Full Text Available The flux creep process in a c-axis Bi2Sr2CaCu2O8+d thin film was investigated at different temperatures and applied fields using the Kim-Anderson (KA approach. The peaked behavior shown in the magnetoresistance profile was attributed to the competing mechanisms of flux motion and sample-intrinsic transition near Tc.Within the temperature range where the competition occurs, U increases with temperature and consequently a decrease in the superconducting volume corresponds to a decrease in the flux creep. Moreover, the flux creep potential barrier varies with applied current I at all temperatures consistent with the KA model.

  8. Investigation of niobium surface structure and composition for improvement of superconducting radio-frequency cavities

    Science.gov (United States)

    Trenikhina, Yulia

    Nano-scale investigation of intrinsic properties of niobium near-surface is a key to control performance of niobium superconducting radio-frequency cavities. Mechanisms responsible for the performance limitations and their empirical remedies needs to be justified in order to reproducibly control fabrication of SRF cavities with desired characteristics. The high field Q-slope and mechanism behind its cure (120°C mild bake) were investigated by comparison of the samples cut out of the cavities with high and low dissipation regions. Material evolution during mild field Q-slope nitrogen treatment was characterized using the coupon samples as well as samples cut out of nitrogen treated cavity. Evaluation of niobium near-surface state after some typical and novel cavity treatments was accomplished. Various TEM techniques, SEM, XPS, AES, XRD were used for the structural and chemical characterization of niobium near-surface. Combination of thermometry and structural temperature-dependent comparison of the cavity cutouts with different dissipation characteristics revealed precipitation of niobium hydrides to be the reason for medium and high field Q-slopes. Step-by-step effect of the nitrogen treatment processing on niobium surface was studied by analytical and structural characterization of the cavity cutout and niobium samples, which were subject to the treatment. Low concentration nitrogen doping is proposed to explain the benefit of nitrogen treatment. Chemical characterization of niobium samples before and after various surface processing (Electropolishing (EP), 800°C bake, hydrofluoric acid (HF) rinsing) showed the differences that can help to reveal the microscopic effects behind these treatments as well as possible sources of surface contamination.

  9. Crystal structure of Nd4Cu2O7

    International Nuclear Information System (INIS)

    Pederzolli, D.R.; Attfield, J.P.

    1998-01-01

    The structure of Nd 4 Cu 2 O 7 (A2/m, a = 8.449 A, b = 3.759 A, c = 12.601 A, β = 109.57 ), prepared by topotactic reduction of the high-T c superconductor parent phase Nd 2 CuO 4 , has been determined from time-of-flight neutron powder diffraction data revealing a new oxygen vacancy-ordered arrangement containing cooperatively distorted Cu 2 O 3 planes in which 2- and 4- coordinate Cu - sites are present. (orig.)

  10. SORPTION OF Cu2+ IONS ONTO DIATOMITE CONSTITUENTS

    Directory of Open Access Journals (Sweden)

    Vasile Rusu

    2009-06-01

    Full Text Available Studies of the sorption capacity towards Cu2+ ions of diatomite from the Ghidirim location of RM, as well as of the extracted clay phase are presented. Separated clay fraction from diatomic material is clean enough, and especially is rich in montmorillonite. Maximum sorption capacity for studied clay fraction is achieved by rising the temperature of calcination treatment up to 200oC. At higher temperatures the lattice of montmorillonite is contracted and its sorption capacity towards Cu2+ ions decreases strongly.

  11. A Diarylethene Derived Chemosensor for Colorimetric Sensing of Cu2+

    Science.gov (United States)

    Pu, Shouzhi; Sun, Qi; Zheng, Chunhong

    2017-07-01

    A diarylethene bearing a 8-hydroxyquinoline-linked salicylhydrazide Schift base unit has been synthesized. In CH3CN, the conpound displayed a highly selective and sensitive response to Cu2+ via perceptible color and UV-vis absorbance changes among the other tested metal ions. In the presence of Cu2+, the peak at 341 nm disappeared and concomitantly a new charge transfer absorption band emerged at 381 and 450 nm. Moreover, the compound formed host-guest complexe in 1:1 stoichiometry.

  12. Responses of mixed methanotrophic consortia to variable Cu2+/Fe2+ ratios.

    Science.gov (United States)

    Chidambarampadmavathy, Karthigeyan; Karthikeyan, Obulisamy Parthiba; Huerlimann, Roger; Maes, Gregory E; Heimann, Kirsten

    2017-07-15

    abundance was ∼2% in the LB- (compared to >50% in CB-CSTR), methane oxidation capacities were comparable in the two systems, suggesting that methane oxidation capacity was maintained by the dominant Azospirllum and Sphingopyxis in the LB-CSTR. Despite similar methanotroph inoculum community composition and controlled environmental variables, increasing Cu 2+ /Fe 2+ ratios resulted in significantly different microbial community structures in the LB- and CB-CSTR, indicative of complex microbial interactions. In summary, our results suggest that a detailed understanding of allelopathic interactions in mixed methanotrophic consortia is vital for constructing robust bio-filters for CH 4 emission abatement. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Fatigue-damage evolution and damage-induced reduction of critical current of a Nb3Al superconducting composite

    International Nuclear Information System (INIS)

    Ochiai, S; Sekino, F; Sawada, T; Ohno, H; Hojo, M; Tanaka, M; Okuda, H; Koganeya, M; Hayashi, K; Yamada, Y; Ayai, N; Watanabe, K

    2003-01-01

    We have studied the fatigue-damage mechanism of a Nb 3 Al superconducting composite at room temperature, and the influences of the fatigue damages introduced at room temperature on the critical current at 4.2 K and the residual strength at room temperature. The main (largest) fatigue crack arose first in the clad copper and then extended into the inner core with an increasing number of stress cycles. The cracking of the Nb 3 Al filaments in the core region occurred at a late stage (around 60-90% of the fatigue life). Once the fracture of the core occurred, it extended very quickly, resulting in a quick reduction in critical current and the residual strength with increasing stress cycles. Such a behaviour was accounted for by the crack growth calculated from the S-N curves (the relation of the maximum stress to the number of stress cycles at failure) combined with the Paris law. The size and distribution of the subcracks along the specimen length, and therefore the reduction in critical current of the region apart from the main crack, were dependent on the maximum stress level. The large subcracks causing fracture of the Nb 3 Al filaments were formed when the maximum stress was around 300-460 MPa, resulting in large reduction in critical current, but not when the maximum stress was outside such a stress range

  14. Lattice parameters values and phase diagram for the Cu2Zn1-zFezGeSe4 alloy system

    International Nuclear Information System (INIS)

    Caldera, D.; Quintero, M.; Morocoima, M.; Quintero, E.; Grima, P.; Marchan, N.; Moreno, E.; Bocaranda, P.; Delgado, G.E.; Mora, A.E.; Briceno, J.M.; Fernandez, J.L.

    2008-01-01

    X-ray powder diffraction and differential thermal analysis (DTA) measurements were made on polycrystalline samples of the Cu 2 Zn 1-z Fe z GeSe 4 alloy system. The diffraction patterns were used to show the equilibrium conditions and to estimate crystalline parameter values. It was found that, at room temperature, a single phase solid solution with the tetragonal stannite α structure (I4-bar2m) occurs across the whole composition range. The DTA thermograms were used to construct the phase diagram of the Cu 2 Zn 1-z Fe z GeSe 4 alloy system. It was confirmed that the Cu 2 ZnGeSe 4 compound melts incongruently. It was observed that undercooling effects occur for samples with z > 0.9

  15. Angle-resolved-photoemission study of Bi2Sr2CaCu2O8+δ: Metallicity of the Bi-O plane

    International Nuclear Information System (INIS)

    Wells, B.O.; Shen, Z.; Dessau, D.S.; Spicer, W.E.; Olson, C.G.; Mitzi, D.B.; Kapitulnik, A.; List, R.S.; Arko, A.

    1990-01-01

    We have performed high-resolution angle-resolved-photoemission experiments on Bi 2 Sr 2 CaCu 2 O 8+δ single crystals with different annealing histories. By depositing a small amount of Au on the surface, we were able to distinguish electronic states associated with the Bi-O surface layer. We found that the Bi-O atomic surface layer is metallic and superconducting for samples that were high-temperature annealed in oxygen but not for as-grown samples. The Cu-O plane is found to be superconducting in all samples

  16. Quantitative Raman Measurement of the Evolution of the Cooper-pair Density with Doping in Bi2Sr2CaCu2O8+δ Superconductors

    International Nuclear Information System (INIS)

    Blanc, S.; Gu, G.; Gallais, Y.; Sacuto, A.; Cazayous, M.; Measson, M.A.; Wen, J.S.; Xu, Z.J.

    2009-01-01

    We report Raman measurements on Bi 2 Sr 2 CaCu 2 O 8+δ single crystals that allow us to quantitatively evaluate the doping dependence of the density of Cooper pairs in the superconducting state. We show that the drastic loss of Cooper pairs in the antinodal region as the doping level is reduced is concomitant with a deep alteration of the quasiparticles dynamic above T c and consistent with a pseudogap that competes with superconductivity. Our data also reveal that the overall density of Cooper pairs evolves with doping, distinctly from the superfluid density above the doping level p c = 0.2.

  17. Synthesis and characterization of thermally evaporated Cu2SnSe3 ternary semiconductor

    Science.gov (United States)

    Hamdani, K.; Chaouche, M.; Benabdeslem, M.; Bechiri, L.; Benslim, N.; Amara, A.; Portier, X.; Bououdina, M.; Otmani, A.; Marie, P.

    2014-11-01

    Copper Tin Selenide (CuSnSe) powder was mechanically alloyed by high energy planetary ball milling, starting from elemental powders. Synthesis time and velocity have been optimized to produce Cu2SnSe3 materials. Thin films were prepared by thermal evaporation on Corning glass substrate at Ts = 300 °C. The structural, compositional, morphological and optical properties of the synthesized semiconductor have been analyzed by X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM) and transmission electron microscopy. The analyzed powder exhibited a cubic crystal structure, with the presence of Cu2Se as a secondary phase. On the other hand, the deposited films showed a cubic Cu2SnSe3 ternary phase and extra peaks belonging to some binary compounds. Furthermore, optical measurements showed that the deposited layers have a relatively high absorption coefficient of 105 cm-1 and present a band gap of 0.94 eV.

  18. Field-induced magnetic instability and quantum criticality in the antiferromagnet CeCu2Ge2.

    Science.gov (United States)

    Liu, Yi; Xie, Donghua; Wang, Xiaoying; Zhu, Kangwei; Yang, Ruilong

    2016-01-13

    The magnetic quantum criticality in strongly correlated electron systems has been considered to be closely related with the occurrence of unconventional superconductivity. Control parameters such as magnetic field, pressure or chemical doping are frequently used to externally tune the quantum phase transition for a deeper understanding. Here we report the research of a field-induced quantum phase transition using conventional bulk physical property measurements in the archetypal antiferromagnet CeCu2Ge2, which becomes superconductive under a pressure of about 10 GPa with Tc ~ 0.64 K. We offer strong evidence that short-range dynamic correlations start appearing above a magnetic field of about 5 T. Our demonstrations of the magnetic instability and the field-induced quantum phase transition are crucial for the quantum criticality, which may open a new route in experimental investigations of the quantum phase transition in heavy-fermion systems.

  19. Physical properties in the normal state of the molecular superconductor Κ-(BEDT)2Cu2(CN)3

    International Nuclear Information System (INIS)

    Papavassiliou, G.C.; Lagouvardos, D.J.; Terzis, A.; Amiell, J.; Garrigou-Lagrange, C.; Delhaes, P.; Hilti, B.; Pfeiffer, J.

    1993-01-01

    We have investigated the electrical, spectroscopic and magnetic properties of the K-phase molecular conductor K-(BEDT) 2 Cu 2 (CN) 3 between room temperature and the liquid He 4 temperature range. We have shown that an intermittent superconducting material is present around or below 4 K which presents above this temperature limited spin fluctuations. The influence of disorder inside the anionic layers is discussed with respect to the X-ray crystal structure, and also the intrinsic effects due to temperature or pressure to explain this situation. Finally, the specific behaviour of the ESR linewidth at low temperature is analysed as a magnetic precursor regime of the supposed superconducting ground state. (orig.)

  20. Effect of 14N ion irradiation on Bi2Sr2CaCu2Oy superconductors

    International Nuclear Information System (INIS)

    Sharma, M.L.; Ashwini Kumar, P.K.; Sarkar, S.K.; Virdi, G.S.; Rup, R.

    1993-01-01

    The effect of 14 N ion irradiation on a bulk Bi 2 Sr 2 CaCu 2 O y high-T c superconducting system has been studied. The incident energy was kept at 150 keV and the irradiation dose varied between 1 x 10 11 cm -2 and 1 x 10 16 cm -2 . It has been observed that the resistive transition occurs at lower temperatures for the irradiated specimens and the width (10-90% transition) of the superconducting transition decreases. Scanning transmission electron microscopy and x-ray diffraction (XRD) studies were carried out to evaluate the change in surface microstructure and XRD peak intensities due to irradiation. The results are discussed in the light of the similarity of atomic sizes of N and O atoms. (author)

  1. Correlated electron state in CeCu2Si2 controlled through Si to P substitution

    Science.gov (United States)

    Lai, Y.; Saunders, S. M.; Graf, D.; Gallagher, A.; Chen, K.-W.; Kametani, F.; Besara, T.; Siegrist, T.; Shekhter, A.; Baumbach, R. E.

    2017-08-01

    CeCu2Si2 is an exemplary correlated electron metal that features two domes of unconventional superconductivity in its temperature-pressure phase diagram. The first dome surrounds an antiferromagnetic quantum critical point, whereas the more exotic second dome may span the termination point of a line of f -electron valence transitions. This behavior has received intense interest, but what has been missing are ways to access the high pressure behavior under milder conditions. Here we study Si → P chemical substitution, which compresses the unit cell volume but simultaneously weakens the hybridization between the f - and conduction electron states and encourages complex magnetism. At concentrations that show magnetism, applied pressure suppresses the magnetic ordering temperature and superconductivity is recovered for samples with low disorder. These results reveal that the electronic behavior in this system is controlled by a nontrivial combination of effects from unit cell volume and electronic shell filling. Guided by this topography, we discuss prospects for uncovering a valence fluctuation quantum phase transition in the broader family of Ce-based ThCr2Si2 -type materials through chemical substitution.

  2. The mechanical deformation of superconducting BiSrCaCuO/Ag composites

    International Nuclear Information System (INIS)

    Han, Z.; Skov-Hansen, P.; Freltoft, T.

    1997-01-01

    The mechanical deformation of BiSrCaCuO/Ag composites made by the powder-in-tube method is a multi-step process. The main difficulty is that the mechanical properties of the ceramic powder are very different from those of the Ag sheath. A key parameter is the core density, which changes during mechanical deformation. In this review, basic concepts of the classical mechanical deformation theory are briefly discussed. Simple descriptions of deformation processes like pressing, rolling, drawing and extrusion are also presented. The term 'freedom parameter', Δ f , is introduced to illustrate the influence of various constraint factors on the mass-flow behaviour. Simple pictures including mass redistribution and the powder-flow model are presented for interpreting the plastic deformation process of the composites. Experimental results are reviewed and our proposed pictures and models are applied for discussion. (author)

  3. The effect of diffusion couple tin content on the superconductivity of filamentary niobium tin composites

    International Nuclear Information System (INIS)

    McDougall, I.L.

    1978-01-01

    The precision with which composites can be designed to meet magnet specifications is improved by considering the effect of non-equilibrium growth in the bronze niobium diffusion couples. Evidence is presented for the suggestion that high growth rates induce lattice microfaulting which reduced Tsub(c) and Hsub(c2) and gives a large gradient in grain size which reduces Jsub(c). (author)

  4. The Development of High Transition Temperature Superconducting Ceramic Thick Films and Wire Composites

    Science.gov (United States)

    1991-12-02

    number of protein or sugar agents were experimented with including Agar, pectin, carboxymethylcellulose, gelatin, alginic acid, xanthan gum , guar gum ...I) Introduction and Description of Scientific Goals 1 II) Material and Powder Synthesis 1 A) Freeze Dried Fabrication of Powders 1 B) Utilization of...composites. II). Material and Powder Synthesis The availability of a reliable technique for producing large quantities of phase pure, submicron powders

  5. Complexation of Cu2+, Ni2+ and UO22+ by radiolytic degradation products of bitumen

    International Nuclear Information System (INIS)

    Loon, L.R. Van; Kopajtic, Z.

    1990-05-01

    The radiolytic degradation of bitumen was studied under conditions which reflect those which will exist in the near field of a cementitious radioactive waste repository. The potential complexation capacity of the degradation products was studied and complexation experiments with Cu 2+ , Ni 2+ and UO 2 2+ were performed. In general 1:1 complexes with Cu 2+ , Ni 2+ and UO 2 2+ , with log K values of between 5.7 and 6.0 for Cu 2+ , 4.2 for Ni 2+ and 6.1 for UO 2 2+ , were produced at an ionic strength of 0.1 M. The composition of the bitumen water was analysed by GC-MS and IC. The major proportion of the bitumen degradation products in solution were monocarboxylic acids (acetic acid, formic acid, myric acid, stearic acid ...), dicarboxylic acids (oxalic acid, phthalic acid) and carbonates. The experimentally derived log K data are in good agreement with the literature and suggest that oxalate determines the speciation of Cu 2+ , Ni 2+ and UO 2 2+ in the bitumen water below pH=7. However, under the high pH conditions typical of the near field of a cementitious repository, competition with OH-ligands will be large and oxalate, therefore, will not play a significant role in the speciation of radionuclides. The main conclusion of the study is that the radiolytic degradation products of bitumen will have no influence on radionuclide speciation in a cementitious near field and, as such, need not to be considered in the appropriate safety assessment models. (author) 12 figs., 11 tabs., 31 refs

  6. Cu2ZnSnS4 thin films grown by flash evaporation and subsequent annealing in Ar atmosphere

    International Nuclear Information System (INIS)

    Caballero, R.; Izquierdo-Roca, V.; Merino, J.M.; Friedrich, E.J.; Climent-Font, A.; Saucedo, E.; 2UB, Departament d'Electrònica, Universitat de Barcelona, C. Martí i Franquès 1, E-08028 Barcelona (Spain))" data-affiliation=" (IREC, Catalonia Institute for Energy Research, C. Jardins de les Dones de Negre 1, Sant Adriá del Besòs, E-08930 Barcelona (Spain); IN2UB, Departament d'Electrònica, Universitat de Barcelona, C. Martí i Franquès 1, E-08028 Barcelona (Spain))" >Pérez-Rodríguez, A.; León, M.

    2013-01-01

    A study of Cu 2 ZnSnS 4 thin films grown by flash evaporation and subsequently annealed in Ar atmosphere has been carried out. Prior to thin film deposition, Cu 2 ZnSnS 4 bulk compounds with stoichiometric and Zn-rich compositions were synthesized as evaporation sources. The characteristics of the bulk compounds and thin films were investigated by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and elastic back scattering. Cu 2 ZnSnS 4 deposited films contain lower concentrations of Zn than the bulk compounds used as evaporation sources, which is related to a preferential Zn re-evaporation during the deposition process. The desired kesterite composition for solar cell applications was achieved by using a Zn-rich compound as the evaporation source plus a thermal treatment at 620 °C in Ar atmosphere. - Highlights: ► Cu 2 ZnSnS 4 (CZTS) thin films by flash evaporation + annealing in Ar atmosphere ► Difficulty of growing a single phase kesterite material ► X-ray diffraction and Raman spectroscopy to identify the different phases ► Importance of the starting film composition to get the desired CZTS material ► Annealing treatment to obtain the optimum material to be used for CZTS solar cells

  7. An Interaction of Rhamnolipids with Cu2+ Ions

    Directory of Open Access Journals (Sweden)

    Jolanta Cieśla

    2018-02-01

    Full Text Available This study was focused on the description of interaction between Cu2+ ions and the 1:1 mono- and dirhamnolipid mixtures in the premicellar and aggregated state in water and 20 mM KCl solution at pH 5.5 and 6.0. The critical micelle concentration of biosurfactants was determined conductometrically and by the pH measurements. Hydrodynamic diameter and electrophoretic mobility were determined in micellar solutions using dynamic light scattering and laser Doppler electrophoresis, respectively. The copper immobilization by rhamnolipids, methylglycinediacetic acid (MGDA, and ethylenediaminetetraacetic acid (EDTA was estimated potentiometrically for the Cu2+ to chelating agent molar ratio from 16:100 to 200:100. The degree of ion binding and the complex stability constant were calculated at a 1:1 metal to chelant molar ratio. The aggregates of rhamnolipids (diameter of 43–89 nm were negatively charged. Biosurfactants revealed the best chelating activities in premicellar solutions. For all chelants studied the degree of metal binding decreased with the increasing concentration of the systems. The presence of K+ lowered Cu2+ binding by rhamnolipids, but did not modify the complex stability significantly. Immobilization of Cu2+ by biosurfactants did not cause such an increase of acidification as that observed in MGDA and EDTA solutions. Rhamnolipids, even in the aggregated form, can be an alternative for the classic chelating agents.

  8. THERMODYNAMIC STUDIES ON THE ADSORPTION OF Cu2+ ...

    African Journals Online (AJOL)

    KEY WORDS: Amine-modified bentonite, TEPA, Heavy metal ions, Adsorption ..... charged due to the isomorphous substitutions within the layers of Al3+ for Si4+ in ... temperature, high temperature was advantageous for Cu2+, Ni2+ and Cd2+ ...

  9. Structural, thermal and optical properties of Cu 2 + doped ...

    Indian Academy of Sciences (India)

    Pure and Cu 2 + doped methacrylic acid–ethyl acrylate (MAA:EA) copolymer films were prepared using thesolution cast technique. The amorphous feature of the copolymer was depicted using X-ray diffraction scans and degreeof crystallinity was found to vary with increasing doping content. UV–Vis absorption spectra in ...

  10. Biosorption of heavy metal copper (Cu2+) by Saccharomyces cerevisiae

    Science.gov (United States)

    Ririhena, S. A. J.; Astuti, A. D.; Fachrul, M. F.; Silalahi, M. D. S.; Hadisoebroto, R.; Rinanti, A.

    2018-01-01

    This research aims to study the optimum effect of contact time and pH adsorption of copper (Cu2+) from electroplating industry waste by dried beer waste S.cerevisiae. This research conducted using batch culture with pH variation 2,3,4,5, and 6, contact time variation 60, 90, 120, 150, 180 minutes, 150 rpm at room temperature (± 28°C), initial Cu2+ concentration 33,746 mg/l, and biosorbent mass 200 mg & 500 mg. The adsorption of heavy metal ions Cu2+ occurs in all variations of pH and contact time at optimum pH. The optimum adsorption occurs at pH 4 with contact time 120 minutes for both 200 mg (41.60%) and 500 mg (61.04%) beer waste biosorbent. Cell morphology seen with Scanning Electron Microscope (SEM) analysis shows the change of cell wall that gets damaged from Cu2+ adsorption. It also proved by the decreased concentration of initial high concentration carboxyl groups. The adsorption process of this research complies to Freundlich Isotherm with R2 value closest to 1 and followed first order kinetic.

  11. Effect of annealing on the superconducting and normal state properties of the doped multifilamentary Cu-Nb composite wires prepared by in situ technique

    International Nuclear Information System (INIS)

    Dubey, S.S.; Dheer, P.N.

    1999-01-01

    The effect of annealing on the superconducting and normal state properties of the Ga-, In-, Ti- and Zr-doped (1 wt%) Cu-Nb composite wires prepared by in situ technique have been investigated in this paper. The wires annealed at 700 C for 10 h and then quenched at room temperature, show a decrease in the superconducting transition temperature, T c , and increase in the transition width, ΔT. Doping of the Cu-Nb wires causes an increase in the normal state resistivity and hence the upper critical field, H C2 . This results in a significant increase of J c . Annealing of these doped samples decreases H C2 and J c . In the case of In- and Ga-doped samples J c shows a marginal improvement at lower field but decreases at higher field. Zr and Ti doping appears to be beneficial for the improved J c in these in situ materials. (orig.)

  12. Analysis of critical current-bend strain relationships in composite Nb3Sn superconducting wires

    International Nuclear Information System (INIS)

    Luhman, T.; Welch, D.O.

    1979-01-01

    In order to be used successfully in fusion magnets, Nb 3 Sn conductors must meet several mechanical strain criteria, including tolerance to bending strains encountered during magnet construction. Since Nb 3 Sn is extremely brittle much information has been generated regarding the sensitivity of these conductros to tensile strain. A recent comparison of critical current-bend and tensile test data indicates that the strain required to initiate compound cracking during bending is significantly less than the strain required to do so by tensile of critical current on bending strains in monofilamentary Nb 3 Sn wires is calculated and compared with experimental data. The calculation takes into account a shift in the composite's neutral axis which occurs during bending. The analysis correctly predicts the observed depdndence of the critical current on bending strains

  13. Superconductivity in filamentary eutectic composites. Progress report, June 1, 1980-May 31, 1980

    International Nuclear Information System (INIS)

    Zaitlin, M.P.

    1980-01-01

    Measurements of electrical resistivity and magnetic susceptibility have been performed as a function of temperature on samples of Nb-Th eutectic composite. Samples with Nb filament radii as small as 38A were used which is considerably less than the coherence length xi in Nb of approx. 380A. Surprisingly, measurements of all samples showed a drop in electrical resistance near the transition temperature of bulk Nb and an unmeasurably small resistance by approx. 8K. The magnetic susceptibility showed essentially perfect diamagnetism below approx. 7 to 9K even for samples with the smallest of filament radii. This is in contradiction to theories of the proximity effect which predict a sharp decrease in the transition temperature for samples with a radius smaller than xi. Some measurements in a static magnetic field have also been made

  14. Study of microstructure and superconducting properties of Nb3Al-tapes, obtained by heat treatment of three-layer and multilayer composites Nb/AlCu

    International Nuclear Information System (INIS)

    Korzhov, Valeriy P.

    2012-01-01

    The structure and superconductivity of three- and multilayer composite tapes of Nb/AlCu after high- temperature heating at 1750-1850 0 C for 1-3 seconds were investigated. Three-layer composites of Nb/AlCu/Nb with thickness of 50 microns were obtained by applying a vacuum rolling at 400-450 0 C and subsequent rolling at room temperature. Multilayer lengthy composites of Nb/AlCu obtained by extrusion with subsequent flattening by rolling of complex blank, collected in a special way. The effect of copper on the structure and properties of three-layer tapes was investigated. Copper increased the critical current of the superconductor. The critical current density in multilayered Nb 3 Al-tape reaches the value 8.10 4 A/cm 2 in magnetic field 14 T. The critical bending radius of the tape is 7 mm. Key words: multilayer composite tape, extrusion, rolling, superconducting Nb 3 Al-tape, high- temperature heat treatment, critical current density

  15. Superconductivity - applications

    International Nuclear Information System (INIS)

    The paper deals with the following subjects: 1) Electronics and high-frequency technology, 2) Superconductors for energy technology, 3) Superconducting magnets and their applications, 4) Electric machinery, 5) Superconducting cables. (WBU) [de

  16. High temperature XRD of Cu2GeSe3

    International Nuclear Information System (INIS)

    Premkumar, D. S.; Malar, P.; Chetty, Raju; Mallik, Ramesh Chandra

    2015-01-01

    The Cu 2 GeSe 3 is prepared by solid state synthesis method. The high temperature XRD has been done at different temperature from 30 °C to 450 °C. The reitveld refinement confirms Cu 2 GeSe 3 phase and orthorhombic crystal structure. The lattice constants are increasing with increase in the temperature and their rate of increase with respect to temperature are used for finding the thermal expansion coefficient. The calculation of the linear and volume coefficient of thermal expansion is done from 30 °C to 400 °C. Decrease in the values of linear expansion coefficients with temperature are observed along a and c axis. Since thermal expansion coefficient is the consequence of the distortion of atoms in the lattice; this can be further used to find the minimum lattice thermal conductivity at given temperature

  17. Relativistic contributions to the bonding in Cu2

    International Nuclear Information System (INIS)

    Martin, R.L.

    1983-01-01

    The influence of relativity on the spectroscopic parameters of Cu 2 has been investigated by evaluating the mass-velocity and one electron Darwin terms of the Breit--Pauli Hamiltonian in the first order of perturbation theory. The relativistic corrections are of the order of 10% of the SCF and GVB results and result in a deeper (approx.1.5 kcal), stiffer (approx.15 cm - 1 ) well, with the bond length contracted by about 0.1a 0

  18. Synthesis and characterization of Cu2+ substituted magnetite

    International Nuclear Information System (INIS)

    Morales, A. L.; Velásquez, A. A.; Urquijo, J. P.; Baggio, E.

    2011-01-01

    Samples of magnetite, both pure and doped with divalent copper, Fe 3 − x Cu x O 4 , with x = 0, 0.05, 0.10 and 0.20 atm.%, were synthesized hydrothermally. The samples were characterized by Atomic Absorption Spectroscopy, Mössbauer Spectroscopy, X-ray diffraction, Scanning Electron Microscopy and SQUID magnetometry. The analyses made by the above techniques showed that as the Cu 2+ concentration increases, a simultaneous reduction in the magnetic and structural parameters takes place, namely: magnetic hyperfine interactions at octahedral sites, particle size and lattice constant. Degradation in the particles morphology as well as a distribution of their size were also observed. Our study points two important effects of Cu 2+ in magnetite, the first one is its incorporation within the structure, replacing Fe 2+ ions and decreasing both the magnetic hyperfine interactions at octahedral sites and the bulk magnetization, the second one is the contraction of the crystalline lattice of magnetite, because incorporation of Cu 2+ within the structure, generation of vacancies or both simultaneous effects.

  19. Magnetic nesting and co-existence of ferromagnetism and superconductivity

    International Nuclear Information System (INIS)

    Elesin, V.F.; Kapaev, V.V.; Kopaev, Yu.V.

    2004-01-01

    In the case of providing for the magnetic nesting conditions of the electron spin dispersion law the co-existence of ferromagnetism and superconductivity is possible by any high magnetization. The co-existence of ferromagnetism and superconductivity in the layered cuprate compounds of the RuSr 2 GdCu 2 O 8 -type is explained on this basis, wherein due to the nonstrict provision of the magnetic nesting condition there exists the finite but sufficiently high critical magnetization [ru

  20. Superconductivity: materials and applications

    International Nuclear Information System (INIS)

    Duchateau, J.L.; Kircher, F.; Leveque, J.; Tixador, P.

    2008-01-01

    This digest paper presents the different types of superconducting materials: 1 - the low-TC superconductors: the multi-filament composite as elementary constituent, the world production of NbTi, the superconducting cables of the LHC collider and of the ITER tokamak; 2 - the high-TC superconductors: BiSrCaCuO (PIT 1G) ribbons and wires, deposited coatings; 3 - application to particle physics: the the LHC collider of the CERN, the LHC detectors; 4 - applications to thermonuclear fusion: Tore Supra and ITER tokamaks; 5 - NMR imaging: properties of superconducting magnets; 6 - applications in electrotechnics: cables, motors and alternators, current limiters, transformers, superconducting energy storage systems (SMES). (J.S.)

  1. Effect of shock pressure on the structure and superconducting properties of Y-Ba-Cu-O in explosively fabricated bulk metal-matrix composites

    Science.gov (United States)

    Murr, L. E.; Niou, C. S.; Pradhan-Advani, M.

    1991-01-01

    While it is now well established that copper-oxide-based power, or virtually any other ceramic superconductor powder, can be consolidated and encapsulated within a metal matrix by explosive consolidation, the erratic superconductivity following fabrication has posed a major problem for bulk applications. The nature of this behavior was found to arise from microstructural damage created in the shock wave front, and the residual degradation in superconductivity was demonstrated to be directly related to the peak shock pressure. The explosively fabricated or shock loaded YBa2Cu3Ox examples exhibit drastically altered rho (or R) - T curves. The deterioration in superconductivity is even more noticeable in the measurement of ac magnetic susceptibility and flux exclusion or shielding fraction which is also reduced in proportion to increasing peak shock pressure. The high frequency surface resistance (in the GHz range) is also correspondingly compromised in explosively fabricated, bulk metal-matrix composites based on YBa2Cu3O7. Transmission electron microscopy (including lattice imaging techniques) is being applied in an effort to elucidate the fundamental (microstructural) nature of the shock-induced degradation of superconductivity and normal state conductivity. One focus of TEM observations has assumed that oxygen displaced from b-chains rather than oxygen-vacancy disorder in the basal plane of oxygen deficient YBa2Cu3Ox may be a prime mechanism. Shock-wave displaced oxygen may also be locked into new positions or interstitial clusters or chemically bound to displaced metal (possibly copper) atoms to form precipitates, or such displacements may cause the equivalent of local lattice cell changes as a result of stoichiometric changes. While the shock-induced suppression of T(sub c) is not desirable in the explosive fabrication of bulk metal-matrix superconductors, it may be turned into an advantage if the atomic-scale distortion can be understood and controlled as local

  2. Electrospinning synthesis of superconducting BSCCO nanowires

    International Nuclear Information System (INIS)

    Duarte, Edgar A.; Quintero, Pedro A.; Meisel, Mark W.; Nino, Juan C.

    2013-01-01

    Highlights: •Bi 2 Sr 2 CaCu 2 O 8+x nanowires 150 nm to 250 nm thick are synthesized using the electrospinning. •Bi 2 Sr 2 CaCu 2 O 8+x nanowires are obtained after a heat treatment at 850 °C. •Bi 2 Sr 2 CaCu 2 O 8+x nanowires show a T c = 78.7 K consistent with bulk superconductor behavior. -- Abstract: This paper presents the synthesis and characterization of Bi 2 Sr 2 CaCu 2 O 8+x superconducting nanowires. Bi 2 Sr 2 CaCu 2 O 8+x nanowires with a T c = 78.7 K are synthesized using the electrospinning process employing sol–gel precursors. A sol–gel methodology is used to obtain a homogeneous PVP solution containing Bi, Sr, Ca, and Cu acetates. Mats of randomly oriented nanowires and aligned nanowires are also collected. After a heat treatment at 850 °C in ambient atmosphere using heating rates of 100 and 400 °C/h, fully crystallized Bi 2 Sr 2 CaCu 2 O 8+x nanowires are obtained. The morphology, microstructure, and crystal structure of these nanowires are then examined to reveal a rectangular morphology having typical wire thickness in the range of 150–250 nm, and a wire width between 400 and 600 nm. DC magnetization studies are conducted to investigate the critical transition temperature (T c ) of Bi 2 Sr 2 CaCu 2 O 8+x nanowires and to compare their magnetic properties to those of bulk Bi 2 Sr 2 CaCu 2 O 8+x powder. The T c for the commercial powder is observed at 78.6 K, and that of the obtained nanowires at 78.7 K. These results point to the superconducting nature of Bi 2 Sr 2 CaCu 2 O 8+x nanowires, and the potential of the electrospinning process for the synthesis of this superconductor material

  3. Superconductivity and magnetism in the ruthenocuprates

    International Nuclear Information System (INIS)

    Klamut, Piotr W

    2008-01-01

    The ruthenocuprates are high temperature superconductors, which have raised a substantial interest due to the simultaneous presence of the transition metal magnetism and superconductivity. The compounds represent a complex and experimentally challenging research arena, with interesting recent experimental developments. The author reviews some key properties of RuSr 2 RECu 2 O 8 , RuSr 2 RE 2-x Ce x Cu 2 O 10-y , and of a few derivative compounds of the ruthenocuprate family. (topical review)

  4. A coumarin-derived Cu2 +-fluorescent chemosensor and its direct application in aqueous media

    Science.gov (United States)

    Mergu, Naveen; Kim, Myeongjin; Son, Young-A.

    2018-01-01

    A novel coumarin-based receptor bearing a benzohydrazide (FCBH) was developed as a fluorescent chemosensor with high selectivity toward Cu2 +. The sensor was successfully applied to the monitoring of Cu2 + in aqueous solution. After the addition of Cu2 + to FCBH, the color of the solution changed from greenish-yellow to red, and the absorption band at 457 nm red-shifted to 517 nm. The fluorescent green color of FCBH disappeared and the fluorescence emission was completely quenched in the presence of Cu2 +. Upon the addition of Cu2 +, deprotonation of FCBH occurred, and a 1:1 metal-ligand complex formed. DFT theoretical investigation was carried out to understand the behavior of the sensing probe toward Cu2 +. Additionally, the quenched fluorescence of the FCBH-Cu2 + complex was restored upon the addition of CN- ions. The possible sensing mechanism of FCBH toward Cu2 + was derived from experimental and theoretical examinations.

  5. Enhanced photocatalytic performance of sandwiched ZnO@Ag@Cu2O nanorod films: the distinct role of Ag NPs in the visible light and UV region

    International Nuclear Information System (INIS)

    Ren, Shoutian; Wang, Yingying; Wang, Benyang; Wang, Qiang; Zhao, Guoliang

    2015-01-01

    Sandwiched ZnO@Ag@Cu 2 O nanorod films were synthesized by successive electrodeposition, magnetron sputtering and the second electrodeposition. The as-synthesized composites were characterized by x-ray diffraction patterns, field emission scanning electron microscopy, low- and high-resolution transmission electron microscopy and a UV–vis spectrophotometer. Their photocatalytic performance was estimated by the degradation of a methyl orange solution under UV or visible-light irradiation, respectively. In the visible region, due to localized surface plasmon resonance absorption of Ag NPs, ZnO@Ag@Cu 2 O showed a significantly enhanced photocatalytic performance. The enhancement factor of Ag NPs on the catalytic performance of ZnO@Ag@Cu 2 O was estimated as a function of the Cu 2 O deposition time, and the corresponding enhancement mechanism was also evaluated by the monochromatic photocatalytic experiment and discrete dipole approximation simulation. In the UV region, due to the formation of a Schottky junction (e.g. Ag/ZnO, Ag/Cu 2 O), a limited enhanced photocatalytic performance was also realized for ZnO@Ag@Cu 2 O photocatalysts. (paper)

  6. Low temperature magnetic properties of NdCu2

    International Nuclear Information System (INIS)

    Hillberg, M.; Wagener, W.; Melo, M.A.C. de; Klauss, H.H.; Litterst, F.J.; Loewenhaupt, W.

    1997-01-01

    μSR experiments on NdCu 2 give evidence for short range order below 25 K above T N =6.5 K. No signal was detected between 16 K and 1.2 K where neutron scattering reveals an incommensurate spin structure. Below 1.2 K the μSR signal is recovered and shows a rotation with 22 MHz. This is interpreted with a squaring up of Nd spins accompanied by a decrease of magnon excitations which is reflected in a decrease of damping of the muon signal

  7. Copper (I) oxide (Cu 2 ) based solar cells - a review | Abdu | Bayero ...

    African Journals Online (AJOL)

    Copper (I) oxide (Cu2O) is a potential material for the fabrication of low cost solar cells for terrestrial application. A detailed survey on the previous work so far carried out on Cu2O based solar cells has been presented. The aspects discussed include the fabrication of Schottky (metal/semiconductor) barrier Cu2O solar cells, ...

  8. Influences of oxygen incorporation on the structural and optoelectronic properties of Cu_2ZnSnS_4 thin films

    International Nuclear Information System (INIS)

    Yu, Ruei-Sung; Hung, Ta-Chun

    2016-01-01

    Highlights: • Oxygen incorporation in Cu_2ZnSnS_4 changes the energy band structure. • The material has a comparatively high-absorptive capacity for short wavelength. • Absorption coefficients of the film increase from 10"4 to 10"5 cm"−"1. • The oxygen-containing CZTS film has a mixture of crystallite and crystalline states. • The material could be a candidate as an absorber layer in multi-junction solar cells. - Abstract: This study used the sol–gel method to prepare Cu_2ZnSnS_4 thin films containing oxygen and explored the composition, structural, and optoelectronic properties of the films. The non-vacuum process enabled the oxygen content of the Cu_2ZnSnS_4 films to be 8.89 at% and 10.30 at% for two different annealing conditions. In the crystal structure, oxygen was substituted at the positions of sulfur and appeared in the interstitial sites of the lattice. The compositions of the thin films deviated from the stoichiometric ratio. Both films had kesterite structures with no secondary phase structure. The kesterite CZTS film possessed a composite microstructure of crystallite and crystalline states. The microstructure of the Cu_2ZnSnS_4 film with higher oxygen content was denser and the average grain size was smaller. Incorporating oxygen atoms into crystalline Cu_2ZnSnS_4 changed the energy band structure: the direct energy band gaps were, respectively, 2.75 eV and 2.84 eV; the thin films mainly adsorbed photons with wavelengths less than 500 nm; and the absorption coefficients increased from 10"4 cm"−"1 to 10"5 cm"−"1. The films had a comparatively high absorptive capacity for photons less than 350 nm. Increasing the oxygen content of the film lowered the resistivity. Thus, the oxygen-containing Cu_2ZnSnS_4 thin film could be a candidate for the p-type absorber layer material required in multi-junction solar cells.

  9. Facile synthesis of Cu2O/CuO/RGO nanocomposite and its superior cyclability in supercapacitor

    International Nuclear Information System (INIS)

    Wang, Kun; Dong, Xiangmao; Zhao, Chongjun; Qian, Xiuzhen; Xu, Yunlong

    2015-01-01

    A reduced graphene oxide (RGO)-based nanocomposite of redox counterpart of the oxides of Cu(I)-Cu(II) pair for Faradaic reaction, Cu 2 O/CuO/RGO, was controllably synthesized through a facile, eco-friendly one-step hydrothermal-assisted redox reaction of elemental Cu and graphene oxide (GO) without the addition of any other reagents. The resultant Cu 2 O/CuO/RGO nanocomposites were characterized by X-ray diffraction (XRD), Raman spectroscopy, Thermogravimetric analysis (TG), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). It is found that, when dealloyed nanoporous Cu was used as a Cu source, the uniform spherical Cu 2 O/CuO nanoparticles with double size scales (∼25 nm and ∼5 nm) were anchored on RGO sheets. This Cu 2 O/CuO/RGO nanocomposite redox counterpart exhibits improved rate capability and excellent cycling stability, i.e., only ca. 21.4% of the capacity was lost when the discharge current density increases from 1 A g −1 (173.4 F g −1 ) to 10 A g −1 (136.3 F g −1 ). Especially, the capacity remains almost unchanged (98.2%) after 100,000 cycles at 10 A g −1 . The good electrochemical performance and simple accessibility prove that this Cu 2 O/CuO/RGO composite consisting of a pair of redox counterparts is a promising material for supercapacitor applications

  10. Electrochemical depositions of fluorohydroxyapatite doped by Cu2+, Zn2+, Ag+ on stainless steel substrates

    International Nuclear Information System (INIS)

    Bir, F.; Khireddine, H.; Touati, A.; Sidane, D.; Yala, S.; Oudadesse, H.

    2012-01-01

    Fluoridated hydroxyapatite (FHA, Ca 10 (PO 4 ) 6 (OH) 2-x F x where 0 2+ , Cu 2+ , Ag + ) substituted fluoridated hydroxyapatite coatings (M-FHA) were deposited on the surface of medical grade 316L stainless steel samples by electrochemical deposition technique. The FHA coatings were co-substituted with antibacterial ions (Zn 2+ , Cu 2+ or Ag + ) by co-precipitation and ion-exchange methods. Characterization studies of coatings from X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDX) showed that the obtained layers are monophase crystals FHA and did not contain any discernible crystalline impurity. The particles of all samples are of nano size that gives thin layers. The surface morphology, microstructure and Ca/P atomic ratio of the FHA coatings can be regulated by varying electrolyte temperature. This later affects the porosity of the coating surface and the chemical compositions of the deposits. Quantitative elemental analysis indicates that the copper, zinc and silver ions are incorporated into the Fluorohydroxyapatite. The antimicrobial effects of doped fluorohydroxyapatite coatings against pathogen bacterial strains Staphylococcus aureus were tested in liquid media. The results are promising and demonstrated that all doped FHA samples exhibit excellent antimicrobial activity “in vitro” against the microorganism, so the antimicrobial properties of the coatings developed are improved.

  11. Superconductivity revisited

    CERN Document Server

    Dougherty, Ralph

    2013-01-01

    While the macroscopic phenomenon of superconductivity is well known and in practical use worldwide in many industries, including MRIs in medical diagnostics, the current theoretical paradigm for superconductivity (BCS theory) suffers from a number of limitations, not the least of which is an adequate explanation of high temperature superconductivity. This book reviews the current theory and its limitations and suggests new ideas and approaches in addressing these issues. The central objective of the book is to develop a new, coherent, understandable theory of superconductivity directly based on molecular quantum mechanics.

  12. Cu2+-labeled dansyl compounds as fluorescent and PET probes for imaging apoptosis.

    Science.gov (United States)

    Han, Junyan; Wang, Xukui; Yu, MeiXiang

    2016-11-15

    Compound DNSTT-Cu 2+ , a novel chelate of Cu 2+ with DOTA conjugated to a fluorescent dansyl fragment, is developed for imaging cell apoptosis. Apoptotic U-87MG cells could be selectively visualized by the fluorescence of DNSTT-Cu 2+ from cytoplasm of cells, confirmed by the fluorescence of apoptosis cells co-labeled with Alexa Fluor 568-labeled annexin V, a conventional probe for selectively labeling membranes of apoptosis cells. A radioactive 64 Cu 2 + analog, DNSTT- 64 Cu 2+ , was easily synthesized, providing a potential PET probe for imaging apoptosis in vivo. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Tuning Bandgap of p-Type Cu2Zn(Sn, Ge)(S, Se)4 Semiconductor Thin Films via Aqueous Polymer-Assisted Deposition.

    Science.gov (United States)

    Yi, Qinghua; Wu, Jiang; Zhao, Jie; Wang, Hao; Hu, Jiapeng; Dai, Xiao; Zou, Guifu

    2017-01-18

    Bandgap engineering of kesterite Cu 2 Zn(Sn, Ge)(S, Se) 4 with well-controlled stoichiometric composition plays a critical role in sustainable inorganic photovoltaics. Herein, a cost-effective and reproducible aqueous solution-based polymer-assisted deposition approach is developed to grow p-type Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films with tunable bandgap. The bandgap of Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films can be tuned within the range 1.05-1.95 eV using the aqueous polymer-assisted deposition by accurately controlling the elemental compositions. One of the as-grown Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films exhibits a hall coefficient of +137 cm 3 /C. The resistivity, concentration and carrier mobility of the Cu 2 ZnSn(S, Se) 4 thin film are 3.17 ohm·cm, 4.5 × 10 16 cm -3 , and 43 cm 2 /(V·S) at room temperature, respectively. Moreover, the Cu 2 ZnSn(S, Se) 4 thin film when used as an active layer in a solar cell leads to a power conversion efficiency of 3.55%. The facile growth of Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films in an aqueous system, instead of organic solvents, provides great promise as an environmental-friendly platform to fabricate a variety of single/multi metal chalcogenides for the thin film industry and solution-processed photovoltaic devices.

  14. Electronic structure in Bi2Sr2CaCu2O8 studied by two dimensional angular correlation of positron annihilation radiations

    International Nuclear Information System (INIS)

    Kondo, H.; Kubota, T.; Nakashima, N.; Tanigawa, S.; Minami, F.; Takekawa, S.

    1992-01-01

    Electronic structure in one of high-Tc-sperconducting materials, Bi 2 Sr 2 CaCu 2 O 8 , was studied by two dimensional angular correlation of positron annihilation radiations (2D-ACAR). The measurements were performed for Bi 2 Sr 2 CaCu 2 O 8 at room temperature and 24K; in the normal and superconducting states. The three dimensional electron momentum density ρ(p) has been reconstructed by using the image reconstruction technique based on a direct Fourier transportation. The reconstructed electron momentum density ρ(p) has been reduced into the reduced electron momentum density n(k) by using the LCW folding procedure. They are compared with that for Cu and Si. The difference in the density distributions between both states was observed. This may be attributed to the smearing by the reduced thermal momenta of positrons. But there is a possibility that the difference is due to the phase transition

  15. Superconductivity in graphite intercalation compounds

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Robert P. [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Weller, Thomas E.; Howard, Christopher A. [Department of Physics & Astronomy, University College of London, Gower Street, London WCIE 6BT (United Kingdom); Dean, Mark P.M. [Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Rahnejat, Kaveh C. [Department of Physics & Astronomy, University College of London, Gower Street, London WCIE 6BT (United Kingdom); Saxena, Siddharth S. [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Ellerby, Mark, E-mail: mark.ellerby@ucl.ac.uk [Department of Physics & Astronomy, University College of London, Gower Street, London WCIE 6BT (United Kingdom)

    2015-07-15

    Highlights: • Historical background of graphite intercalates. • Superconductivity in graphite intercalates and its place in the field of superconductivity. • Recent developments. • Relevant modeling of superconductivity in graphite intercalates. • Interpretations that pertain and questions that remain. - Abstract: The field of superconductivity in the class of materials known as graphite intercalation compounds has a history dating back to the 1960s (Dresselhaus and Dresselhaus, 1981; Enoki et al., 2003). This paper recontextualizes the field in light of the discovery of superconductivity in CaC{sub 6} and YbC{sub 6} in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how these relate to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic states and phonon modes are most important for superconductivity, and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition.

  16. Superconductivity in graphite intercalation compounds

    International Nuclear Information System (INIS)

    Smith, Robert P.; Weller, Thomas E.; Howard, Christopher A.; Dean, Mark P.M.; Rahnejat, Kaveh C.; Saxena, Siddharth S.; Ellerby, Mark

    2015-01-01

    Highlights: • Historical background of graphite intercalates. • Superconductivity in graphite intercalates and its place in the field of superconductivity. • Recent developments. • Relevant modeling of superconductivity in graphite intercalates. • Interpretations that pertain and questions that remain. - Abstract: The field of superconductivity in the class of materials known as graphite intercalation compounds has a history dating back to the 1960s (Dresselhaus and Dresselhaus, 1981; Enoki et al., 2003). This paper recontextualizes the field in light of the discovery of superconductivity in CaC 6 and YbC 6 in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how these relate to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic states and phonon modes are most important for superconductivity, and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition

  17. Alteration of the superconducting properties of A15 compounds and elementary composite superconductors by non-hydrostatic elastic strain

    International Nuclear Information System (INIS)

    Welch, D.O.

    1979-01-01

    Elastic strains alter (usually, but not always, adversely) the critical temperatures, magnetic fields, and current densities of superconducting A15 compounds; non-hydrostatic strain states are particularly effective in this regard. This paper is a review of the experimental evidence, obtained by a variety of techniques, concerning the strain dependence of the critical properties of a number of A15 compounds and a discussion of theoretical models for describing such effects

  18. Construction of Hierarchical CuO/Cu2O@NiCo2S4 Nanowire Arrays on Copper Foam for High Performance Supercapacitor Electrodes

    Science.gov (United States)

    Zhou, Luoxiao; He, Ying; Jia, Congpu; Pavlinek, Vladimir; Saha, Petr; Cheng, Qilin

    2017-01-01

    Hierarchical copper oxide @ ternary nickel cobalt sulfide (CuO/Cu2O@NiCo2S4) core-shell nanowire arrays on Cu foam have been successfully constructed by a facile two-step strategy. Vertically aligned CuO/Cu2O nanowire arrays are firstly grown on Cu foam by one-step thermal oxidation of Cu foam, followed by electrodeposition of NiCo2S4 nanosheets on the surface of CuO/Cu2O nanowires to form the CuO/Cu2O@NiCo2S4 core-shell nanostructures. Structural and morphological characterizations indicate that the average thickness of the NiCo2S4 nanosheets is ~20 nm and the diameter of CuO/Cu2O core is ~50 nm. Electrochemical properties of the hierarchical composites as integrated binder-free electrodes for supercapacitor were evaluated by various electrochemical methods. The hierarchical composite electrodes could achieve ultrahigh specific capacitance of 3.186 F cm−2 at 10 mA cm−2, good rate capability (82.06% capacitance retention at the current density from 2 to 50 mA cm−2) and excellent cycling stability, with capacitance retention of 96.73% after 2000 cycles at 10 mA cm−2. These results demonstrate the significance of optimized design and fabrication of electrode materials with more sufficient electrolyte-electrode interface, robust structural integrity and fast ion/electron transfer. PMID:28914819

  19. Construction of Hierarchical CuO/Cu2O@NiCo2S4 Nanowire Arrays on Copper Foam for High Performance Supercapacitor Electrodes

    Directory of Open Access Journals (Sweden)

    Luoxiao Zhou

    2017-09-01

    Full Text Available Hierarchical copper oxide @ ternary nickel cobalt sulfide (CuO/Cu2O@NiCo2S4 core-shell nanowire arrays on Cu foam have been successfully constructed by a facile two-step strategy. Vertically aligned CuO/Cu2O nanowire arrays are firstly grown on Cu foam by one-step thermal oxidation of Cu foam, followed by electrodeposition of NiCo2S4 nanosheets on the surface of CuO/Cu2O nanowires to form the CuO/Cu2O@NiCo2S4 core-shell nanostructures. Structural and morphological characterizations indicate that the average thickness of the NiCo2S4 nanosheets is ~20 nm and the diameter of CuO/Cu2O core is ~50 nm. Electrochemical properties of the hierarchical composites as integrated binder-free electrodes for supercapacitor were evaluated by various electrochemical methods. The hierarchical composite electrodes could achieve ultrahigh specific capacitance of 3.186 F cm−2 at 10 mA cm−2, good rate capability (82.06% capacitance retention at the current density from 2 to 50 mA cm−2 and excellent cycling stability, with capacitance retention of 96.73% after 2000 cycles at 10 mA cm−2. These results demonstrate the significance of optimized design and fabrication of electrode materials with more sufficient electrolyte-electrode interface, robust structural integrity and fast ion/electron transfer.

  20. O 1s core levels in Bi2Sr2CaCu2O8+δ single crystals

    International Nuclear Information System (INIS)

    Parmigiani, F.; Shen, Z.X.; Mitzi, D.B.; Lindau, I.; Spicer, W.E.; Kapitulnik, A.

    1991-01-01

    High-quality Bi 2 Sr 2 CaCu 2 O 8+δ superconducting single crystals, annealed at different oxygen partial pressures, have been studied using angular-resolved x-ray photoelectron spectroscopy with a resolution higher than that used in any previous study. Two states of the oxygen, separated by ∼0.7 eV, are unambiguously observed. Examining these components at different angles makes it possible to distinguish bulk from surface components. Using this capability we discover that annealing under lower oxygen partial pressure (1 atm) results in oxygen intercalation beneath the Bi-O surface layer of the crystal, whereas for higher-pressure anneals (12 atm) additional oxygen is found on the Bi-O surfaces. This steplike intercalation mechanism is also confirmed by the changes observed in the Cu and Bi core lines as a function of the annealing oxygen partial pressure

  1. Superstructure of the superconductor BI2Sr2CaCu2O8 by high resolution electron microscopy

    International Nuclear Information System (INIS)

    Hewat, E.A.

    1988-01-01

    The superstructure of the high Tc superconducting oxide BI 2S r 2C aCu 2 0 8 has been studied by high resolution electron microscopy. Waves of distortion along the b-axis give an incommensurate superlattice slightly larger or smaller than 5√2a p (a p = perovskite unit cell). The building blocks along the b-axis are 4, 5 and 6 times √2a p /2. The incommensurate superlattice is composed of approximately periodic combinations of these building blocks. The symmetry of three major projections are P gm (or possibly P gg ), C mm and C mm for the ideal superlattice with b=5√ 2a p . These projections correspond to the space groups Pcnn and Pmnn respectively

  2. Effect of Ag on the peritectic decomposition of Bi2Sr2CaCu2Ox

    International Nuclear Information System (INIS)

    Margulies, L.; Dennis, K.W.; Kramer, M.J.; McCallum, R.W.

    1995-01-01

    During the melt processing of superconducting wires and tapes a number of partial liquid phase regions are entered, and the type and amount of second phases that exist in the melt before cooling are critical in determining the microstructure of the final material. Decomposition pathway of Bi 2 Sr 2 CaCu 2 O x (Bi2212) with 0, 2, and 10 wt% Ag added was examined at 1 bar PO 2 by performing SAME/EDS analysis on oil quenched samples. A variety of quaternary phase diagrams were constructed to describe the evolution of the phase assemblage with temperature. At all Ag contents, Bi2212 first undergoes a peritectic reaction producing (Sr 1-x Ca x ) 14 Cu 24 O 41 (14,24), Bi 2 (Sr 1-x Ca x ) 4 O x (24x), and liquid

  3. The CdS/Cu2S solar cell. 2

    International Nuclear Information System (INIS)

    Boeer, K.W.

    1981-01-01

    The present state of the art in theory and experimental knowledge of the operation of CdS/Cu 2 S solar cells is reviewed. The subject is covered under the following headings: (1) voltage drop across the cell, (2) Boltzmann solution near the open circuit voltage, (3) boundary condition at the junction-emitter interface, (4) current-voltage characteristics, (5) multiple donors (traps) in the junction, (6) space charge and field limitation caused by field quenching, (7) tunneling under reverse bias, (8) current-dependent interface electron density and interface recombination, (9) kinetics of the characteristics, (10) relevant experimental results, (11) deduction of junction parameters from j-U characteristics, and (12) junction-emitter interface. 37 references are included

  4. Superconducting Bi-Sr-Ca-Cu-O thin films from metallo-organic complexes

    International Nuclear Information System (INIS)

    Gruber, H.; Krautz, E.; Fritzer, H.P.; Popitsch, A.

    1991-01-01

    Thin films in the Bi-Sr-Ca-Cu-O system are produced by decomposition of organic precursor compounds containing different metallo-organic complexes. The superconducting phase identified is Bi 2 Sr 2 CaCu 2 O 8+x on (100)-MgO single crystal substrates, polycrystalline Au- and Ag-ribbons and Bi 2 Sr 2 Ca 2 Cu 3 O 10+x on Ag-ribbons. For the 2212-phase a zero resistance temperature of 79 K is found. The 2223-samples on Ag-ribbons show a broad transition at 110 K with a zero resistance at 85 K. SEM and EDX are used for the detection of the microstructure and composition of the prepared films. (orig.)

  5. Superconducting technology

    International Nuclear Information System (INIS)

    2010-01-01

    Superconductivity has a long history of about 100 years. Over the past 50 years, progress in superconducting materials has been mainly in metallic superconductors, such as Nb, Nb-Ti and Nb 3 Sn, resulting in the creation of various application fields based on the superconducting technologies. High-T c superconductors, the first of which was discovered in 1986, have been changing the future vision of superconducting technology through the development of new application fields such as power cables. On basis of these trends, future prospects of superconductor technology up to 2040 are discussed. In this article from the viewpoints of material development and the applications of superconducting wires and electronic devices. (author)

  6. Interface superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Gariglio, S., E-mail: stefano.gariglio@unige.ch [DQMP, Université de Genève, 24 Quai E.-Ansermet, CH-1211 Genève (Switzerland); Gabay, M. [Laboratoire de Physique des Solides, Bat 510, Université Paris-Sud 11, Centre d’Orsay, 91405 Orsay Cedex (France); Mannhart, J. [Max Planck Institute for Solid State Research, 70569 Stuttgart (Germany); Triscone, J.-M. [DQMP, Université de Genève, 24 Quai E.-Ansermet, CH-1211 Genève (Switzerland)

    2015-07-15

    Highlights: • We discuss interfacial superconductivity, a field boosted by the discovery of the superconducting interface between LaAlO. • This system allows the electric field control and the on/off switching of the superconducting state. • We compare superconductivity at the interface and in bulk doped SrTiO. • We discuss the role of the interfacially induced Rashba type spin–orbit. • We briefly discuss superconductivity in cuprates, in electrical double layer transistor field effect experiments. • Recent observations of a high T{sub c} in a monolayer of FeSe deposited on SrTiO{sub 3} are presented. - Abstract: Low dimensional superconducting systems have been the subject of numerous studies for many years. In this article, we focus our attention on interfacial superconductivity, a field that has been boosted by the discovery of superconductivity at the interface between the two band insulators LaAlO{sub 3} and SrTiO{sub 3}. We explore the properties of this amazing system that allows the electric field control and on/off switching of superconductivity. We discuss the similarities and differences between bulk doped SrTiO{sub 3} and the interface system and the possible role of the interfacially induced Rashba type spin–orbit. We also, more briefly, discuss interface superconductivity in cuprates, in electrical double layer transistor field effect experiments, and the recent observation of a high T{sub c} in a monolayer of FeSe deposited on SrTiO{sub 3}.

  7. Removal of Cu2+ and turbidity from wastewater by mercaptoacetyl chitosan.

    Science.gov (United States)

    Chang, Qing; Zhang, Min; Wang, Jinxi

    2009-09-30

    A macromolecule heavy metal flocculant mercaptoacetyl chitosan (MAC) was prepared by reacting chitosan with mercaptoacetic acid. In preliminary experiments, the flocculation performance of MAC was evaluated by using wastewater containing Cu(2+) or/and turbidity. Some factors which affect the removal of Cu(2+) and turbidity were also studied. The experimental results showed that: (1) MAC can remove both Cu(2+) and turbidity from wastewater. The removal efficiency of Cu(2+) by using MAC combined with hydrolyzed polyacrylamide is higher than that by only using MAC, the removal efficiency of Cu(2+) reaches above 98%; (2) when water sample containing not only Cu(2+) but also turbidity-causing substance, the removal efficiency of both Cu(2+) and turbidity will be promoted by the cooperation effect of each other, the residual concentration of Cu(2+) reaches below 0.5 mg L(-1) and the turbidity reaches below 3NTU, Cu(2+) is more easily removed by MAC when turbidity is higher; (3) the removal efficiency of Cu(2+) increases with the increase in pH value, contrarily removal efficiency of turbidity decreases with the increase in pH value.

  8. Effects of supporting electrolyte on galvanic deposition of Cu2O crystals

    International Nuclear Information System (INIS)

    Wang Lida; Liu Guichang; Xue Dongfeng

    2011-01-01

    Highlights: → The effects of electrolyte on the galvanic deposition of Cu 2 O crystals have been investigated. → The chemical nature of supporting electrolyte plays important roles in the galvanic deposition of Cu 2 O crystals. → Cubic Cu 2 O crystals are formed in chloride electrolytes. → Truncated octahedral Cu 2 O crystals are produced in nitrate, sulfate and fluoride electrolytes. - Abstract: The effects of introduced supporting electrolyte on the galvanic deposition of Cu 2 O crystals have been investigated using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD). The results show that the chemical nature of supporting electrolytes plays very important roles in the galvanic deposition of Cu 2 O crystals. The chloride stabilizes the (1 0 0) planes of Cu 2 O crystals, resulting in the formation of cubic crystals, while nitrate, sulfate and fluoride stabilize the (1 1 1) planes of Cu 2 O crystals, leading to the deposition of truncated octahedral and octahedral Cu 2 O crystals. It provides a facile way to control the morphology of galvanically obtained Cu 2 O crystals by indirectly adjusting the inorganic adsorption agents.

  9. Magnetic penetration depth and flux dynamics in single-crystal Bi2Sr2CaCu2O8+δ

    International Nuclear Information System (INIS)

    Harshman, D.R.; Kleiman, R.N.; Inui, M.; Espinosa, G.P.; Mitzi, D.B.; Kapitulnik, A.; Pfiz, T.; Williams, D.L.

    1991-01-01

    The muon-spin-relaxation technique has been used to study vortex dynamics in single-phase superconducting single crystals of Bi 2 Sr 2 CaCu 2 O 8+δ (T c ∼90 K). The data indicate motional narrowing of the internal field distribution due to vortex motion (on a time scale comparable to the muon lifetime). A field-dependent lattice transition is also observed at T x ∼30 K, as evidenced by the onset of an asymmetric line shape below T x . Narrowing arising from disordering of the vortices along [001] is also discussed with reference to its effect on the measured penetration depth

  10. Pair momentum distribution in Bi2Sr2CaCu2O8+δ measured by positron annihilation: Existence and nature of the Fermi surface

    International Nuclear Information System (INIS)

    Chan, L.P.; Harshman, D.R.; Lynn, K.G.; Massidda, S.; Mitzi, D.B.

    1991-01-01

    We report the first measurement of the positron-electron momentum density in superconducting single-crystal Bi 2 Sr 2 CaCu 2 O 8+δ (T c ∼90 K). The observed anisotropy exhibits a twofold (rather than fourfold) symmetry, which is attributed to the superlattice modulation along the b axis of the BiO 2 layers. Subtraction of the superlattice contribution also reveals a pair momentum distribution consistent with the CuO 2 and BiO 2 Fermi surfaces, and in reasonable agreement with the theoretical pair momentum density derived from band theory

  11. Pair momentum distribution in Bi2Sr2CaCu2O(8+delta) measured by positron annihilation - Existence and nature of the Fermi surface

    Science.gov (United States)

    Chan, L. P.; Lynn, K. G.; Harshman, D. R.; Massidda, S.; Mitzi, D. B.

    1991-09-01

    The first measurement is reported of the position-electron momentum density in superconducting single-crystal Bi2Sr2CaCu2O(8+delta)(Tc roughly 90 K). The observed anisotropy exhibits a twofold (rather than fourfold) symmetry, which is attributed to the superlattice modulation along the b axis of the BiO2 layers. Subtraction of the superlattice contribution also reveals a pair momentum distribution consistent with the CuO2 and BiO2 Fermi surfaces, and in reasonable agreement with the theoretical pair momentum density derived from band theory.

  12. Temperature dependence of the phonon structure in the high-temperature superconductor Bi2Sr2CaCu2O8 studied by infrared reflectance spectroscopy

    International Nuclear Information System (INIS)

    Kamaras, K.; Herr, S.L.; Porter, C.D.; Tanner, D.B.; Etemad, S.; Tarascon, J.

    1991-01-01

    We have investigated a ceramic sample of the high-temperature superconductor Bi 2 Sr 2 CaCu 2 O 8 (T c =85 K) by infrared and visible reflectance spectroscopy at several temperatures both below and above the superconducting transition. We find that the temperature variation in the vibrational region is associated with minima or antiresonance features of the optical conductivity, instead of maxima, indicating strong Fano-type electron-phonon interaction and implying that the phonon structure in the infrared is strongly affected by the ab-plane response

  13. Large Tc depression at low angle [100] tilt grain boundaries in bulk Bi2Sr2CaCu2O8+δ bicrystals

    International Nuclear Information System (INIS)

    Li, Q.; Tsay, Y.N.; Zhu, Y.; Suenaga, M.; Gu, G.D.; Koshizuka, N.

    1997-01-01

    Large depression of T c at 7 degree [100] tilt grain boundaries was observed in bulk Bi 2 Sr 2 CaCu 2 O 8+δ (Bi2212) bicrystals by measuring the zero-field electrical transport properties of the grain boundaries and the constituent single crystals over an extended range of currents and voltages. The T c -depressed region was determined to be around 20 nm, comparable to the width of the strain field associated with the observed array of grain-boundary dislocations. Superconducting coupling of the grain boundaries increases sharply as temperature decreases below the grain-boundary T c congruent 68 K. copyright 1997 American Institute of Physics

  14. Large effect of columnar defects on the thermodynamic properties of Bi2Sr2CaCu2O8 single crystals

    Science.gov (United States)

    van der Beek, C. J.; Konczykowski, M.; Li, T. W.; Kes, P. H.; Benoit, W.

    1996-07-01

    The introduction of columnar defects by irradiation with 5.8-GeV Pb ions is shown to affect significantly the reversible magnetic properties of Bi2Sr2CaCu2O8+δ single crystals. Notably, the suppression of superconducting fluctuations on length scales greater than the separation between columns leads to the disappearance of the ``crossing point'' in the critical fluctuation regime. At lower temperatures, the strong modification of the vortex energy due to pinning leads to an important change of the reversible magnetization. The analysis of the latter permits the direct determination of the pinning energy.

  15. Distribution of local critical current along sample length and its relation to overall current in a long Bi2223/Ag superconducting composite tape

    International Nuclear Information System (INIS)

    Ochiai, S; Doko, D; Okuda, H; Oh, S S; Ha, D W

    2006-01-01

    The distribution of the local critical current and the n-value along the sample length and its relation to the overall critical current were studied experimentally and analytically for the bent multifilamentary Bi2223/Ag/Ag-Mg alloy superconducting composite tape. Then, based on the results, it was attempted to simulate on a computer the dependence of the critical current on the sample length. The main results are summarized as follows. The experimentally observed relation of the distributed local critical current and n-value to the overall critical current was described comprehensively with a simple voltage summation model, in which the sample was regarded as a one-dimensional series circuit. The sample length dependence of the critical current was reproduced on the computer by a Monte Carlo simulation incorporating the voltage summation model and the regression analysis results for the local critical current distribution and the relation of the n-value to the critical current

  16. Organic superconductivity

    International Nuclear Information System (INIS)

    Jerome, D.

    1980-01-01

    We present the experimental evidences for the existence of a superconducting state in the Quasi One Dimensional organic conductor (TMTSF) 2 PF 6 . Superconductivity occuring at 1 K under 12 kbar is characterized by a zero resistance diamagnetic state. The anistropy of the upper critical field of this type II superconductor is consistent with the band structure anistropy. We present evidences for the existence of large superconducting precursor effects giving rise to a dominant paraconductive contribution below 40 K. We also discuss the anomalously large pressure dependence of T sb(s), which drops to 0.19 K under 24 kbar in terms of the current theories. (author)

  17. A turn-on fluorescent rhodamine-acyl hydrazide for selective detection of Cu"2"+ ions

    International Nuclear Information System (INIS)

    Yoon, Jung Won; Jeong, Hyuk; Lee, Min Hee

    2017-01-01

    We present a rhodamine-based probe that can detect Cu"2"+ ions via Cu"2"+-promoted hydrolysis in aqueous solutions. In solution, the probe is non-fluorescent and colorless, but gives a strong fluorescence at 586 nm and shows a color change to pink on the addition of Cu"2"+ ions. We demonstrate that the rhodamine-based probe undergoes Cu"2"+-promoted hydrolysis with a moderate reaction time (within 3 min) and provides a fluorescence off–on change, even in the presence of other competitive metal ions. The rhodamine-based probe shows a linear correlation between increasing fluorescence at 586 nm and the Cu"2"+ concentration, and can detect Cu"2"+ at nanomolar levels (10 nM) in CH_3CN:H_2O (v/v, 90:10)

  18. Large-scale synthesis of hierarchical-structured weissite (Cu2−xTe) flake arrays and their catalytic properties

    International Nuclear Information System (INIS)

    Cao, Xinjiang; Yan, Shancheng; Ortiz, Lazarus Santiago; Liang, Gaofeng; Sun, Bo; Huang, Ningping; Xiao, Zhongdang

    2014-01-01

    Graphical abstract: - Highlights: • Large-scale Cu 2−x Te flake arrays grown on copper foam were synthesized. • They possess superior catalytic efficiency on methylene blue with the assistance of H 2 O 2 . • The effects of preparing conditions on the growth of Cu 2−x Te flake arrays were investigated. - Abstract: Large-scale weissite (Cu 2−x Te) flake arrays with three-dimensional (3D) hierarchical structure have been successfully fabricated via a facile one-step solution-phase strategy through the reaction of tellurium powder and copper foam. At the end of the reaction Cu 2−x Te flakes were distributed evenly on the surface of a porous solid copper substrate. Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis showed the abundance of flakes grown on the 3D porous copper architecture, while X-ray diffraction (XRD) and energy-dispersive X-ray spectra (EDS) were used to determine the crystal structure and phase composition of these products. A series of experiments discovered that the size and morphology of the products could be affected by some reactive parameters including the reaction time, synthesis temperature and volume ratio of absolute ethanol/deionized water. Catalysis experiments using the in situ synthesized of Cu 2−x Te flakes to catalyze the degradation of methylene blue (MB) demonstrated the strong catalytic ability of these flakes

  19. Chronological change of electrical resistance in GeCu2Te3 amorphous film induced by surface oxidation

    International Nuclear Information System (INIS)

    Saito, Yuta; Shindo, Satoshi; Sutou, Yuji; Koike, Junichi

    2014-01-01

    Unusual chronological electrical resistance change behavior was investigated for amorphous GeCu 2 Te 3 phase change material. More than a 1 order decrease of electrical resistance was observed in the air even at room temperature. The resistance of the amorphous film gradually increased with increasing temperature and then showed a drop upon crystallization. Such unusual behavior was attributed to the oxidation of the amorphous GeCu 2 Te 3 film. From the compositional depth profile measurement, the GeCu 2 Te 3 film without any capping layer was oxidized in air at room temperature and the formed oxide was mainly composed of germanium oxide. Consequently, a highly-conductive Cu-rich layer was formed in the vicinity of the surface of the film, which reduced the total resistance of the film. The present results could provide insight into the chronological change of electrical resistance in amorphous chalcogenide materials, indicating that not only relaxation of the amorphous, but also a large atomic diffusion contributes to the chronological resistance change. (paper)

  20. Importance of controlling the Tl-oxide partial pressure throughout the processing of TlBa2CaCu2O7 thin films

    International Nuclear Information System (INIS)

    Siegal, M.P.; Venturini, E.L.; Newcomer, P.P.; Overmyer, D.L.; Dominguez, F.; Dunn, R.

    1995-01-01

    TlBa 2 CaCu 2 O 7 (Tl-1212) superconducting films 5000--6000 A thick have been grown on LaAlO 3 (100) substrates using oxide precursors in a closed two-zone thallination furnace. Tl-1212 films can be grown with transition temperatures ∼100 K, and critical current densities measured by magnetization of J cm (5 K)>10 7 A/cm 2 and J cm (77 K)>10 5 A/cm 2 . Processing conditions, substrate temperatures and Tl-oxide source temperatures are found which result in smooth, nearly phase-pure Tl-1212 films. Variations in the respective temperature ramps of the Tl-oxide zone and the substrate zone can greatly influence resulting film properties such as microstructure, morphology, superconducting transition temperature, and critical current density. copyright 1995 American Institute of Physics

  1. Quench studies on a layer-wound Bi2Sr2CaCu2Ox/AgX coil at 4.2 K

    International Nuclear Information System (INIS)

    Trociewitz, U P; Czabaj, B; Hong, S; Huang, Y; Knoll, D C; Larbalestier, D C; Markiewicz, W D; Miao, H; Meinesz, M; Wang, X; Schwartz, J

    2008-01-01

    To evaluate the controlled quench behavior of high temperature superconducting (HTS) coils, particularly when using HTS coils in a hybrid configuration as an insert in a low temperature superconducting magnet, a layer-wound solenoid using Bi 2 Sr 2 CaCu 2 O wire was instrumented with several strip heaters to generate quenches in the axial and azimuthal directions. An array of distributed voltage taps and thermocouples were used to monitor the quench signals. Minimum quench energies (MQE) and quench propagation velocities (NZPVs) were determined. Results show that quench energies were moderate. NZPVs were slow but quench reaction times were of the same order as reaction times obtained at low quench energy densities in Nb 3 Sn coils

  2. Preparation of ZnO/Cu2O compound photocatalyst and application in treating organic dyes

    International Nuclear Information System (INIS)

    Xu Chao; Cao Lixin; Su Ge; Liu Wei; Liu Hui; Yu Yaqin; Qu Xiaofei

    2010-01-01

    ZnO/Cu 2 O compound photocatalysts were prepared by 'soak-deoxidize-air oxidation' with different concentrations of Cu 2+ (0.125, 0.25, 0.5, 1, 1.5 and 2 mol/L). The prepared ZnO/Cu 2 O samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS), UV-vis diffuse reflectance spectrometer, and photochemical reaction instrument. The results show that ZnO was hexagonal wurtzite structure and the crystallinity had no change with the increase of Cu 2+ concentration. Cu 2 O belonged to cubic structure and the crystallinity increased with the increase of Cu 2+ concentration. ZnO were rods and bulks which had diameter of about 300-400 nm, some small round Cu 2 O particles which had a diameter of about 50 nm adhered to these rods and bulks. In the compounds the mole ratio of Cu 2 O to ZnO was 0.017, 0.025, 0.076, 0.137, 0.138, and 0.136, respectively. An absorbance in the visible light region between 400 and 610 nm was seen and the reflection rate became less with the mole ratio of Cu 2 O to ZnO increasing. The photocatalytic activities of ZnO/Cu 2 O compound were evaluated using a basic organic dye, methyl orange (MO). It was found that, compared with pure ZnO, the photocatalytic properties of ZnO/Cu 2 O compound were improved greatly and some compounds were better than pure Cu 2 O.

  3. Tunneling spectroscopy of heavily underdoped crystals of Bi2Sr2CaCu2O8+δ

    International Nuclear Information System (INIS)

    Ozyuzer, L.; Zasadzinski, J.F.; Miyakawa, N.; Kendziora, C.; Jian, S.; Hinks, D. G.; Gray, K.E.

    2000-01-01

    Crystals of Bi 2 Sr 2 CaCu 2 O 8+δ with optimal Tc = 95 K have been underdoped using two different methods and the superconducting gaps have been obtained by tunneling. In some cases, three different tunneling geometries have been utilized: point contact, STM and break junctions. The first doping method involves control of the oxygen content by annealing in various partial pressures of oxygen. These crystals exhibit a narrow spread of gap values over a wide doping range from overdoped (Tc = 56 K) to underdoped with Tc = 70 K. However, for underdoped crystals with Tc midpoints in the range 25 K--63 K, there is a dramatic increase in the spread of gap values which may signal the development of static phase separation of either chemical or electronic origin. To avoid possible chemical phase separation, the authors have explored another doping procedure which incorporates Dy substitution on the Ca site. These crystals exhibit a relatively narrow superconducting transition width and some preliminary tunneling spectra will be presented

  4. Superconducting linac

    International Nuclear Information System (INIS)

    Bollinger, L.M.; Shepard, K.W.; Wangler, T.P.

    1978-01-01

    This project has two goals: to design, build, and test a small superconducting linac to serve as an energy booster for heavy ions from an FN tandem electrostatic accelerator, and to investigate various aspects of superconducting rf technology. The main design features of the booster are described, a status report on various components (resonators, rf control system, linac control system, cryostats, buncher) is given, and plans for the near future are outlined. Investigations of superconducting-linac technology concern studies on materials and fabrication techniques, resonator diagnostic techniques, rf-phase control, beam dynamics computer programs, asymmetry in accelerating field, and surface-treatment techniques. The overall layout of the to-be-proposed ATLAS, the Argonne Tandem-Linac Accelerator System, is shown; the ATLAS would use superconducting technology to produce beams of 5 to 25 MeV/A. 6 figures

  5. Superconducting materials

    International Nuclear Information System (INIS)

    Kormann, R.; Loiseau, R.; Marcilhac, B.

    1989-01-01

    The invention concerns superconducting ceramics containing essentially barium, calcium and copper fluorinated oxides with close offset and onset temperatures around 97 K and 100 K and containing neither Y nor rare earth [fr

  6. Hole superconductivity

    International Nuclear Information System (INIS)

    Hirsch, J.E.; Marsiglio, F.

    1989-01-01

    The authors review recent work on a mechanism proposed to explain high T c superconductivity in oxides as well as superconductivity of conventional materials. It is based on pairing of hole carriers through their direct Coulomb interaction, and gives rise to superconductivity because of the momentum dependence of the repulsive interaction in the solid state environment. In the regime of parameters appropriate for high T c oxides this mechanism leads to characteristic signatures that should be experimentally verifiable. In the regime of conventional superconductors most of these signatures become unobservable, but the characteristic dependence of T c on band filling survives. New features discussed her include the demonstration that superconductivity can result from repulsive interactions even if the gap function does not change sign and the inclusion of a self-energy correction to the hole propagator that reduces the range of band filling where T c is not zero

  7. ANTIMICROBIAL ACTIVITY OF Ag+, Cu2+, Zn2+, Mg2+ IONS DOPED CHITOSAN NANOPARTICLES

    Directory of Open Access Journals (Sweden)

    Sukhodub LB

    2015-04-01

    Full Text Available Modification by polymers and inorganic ions of the bioactive materials for orthopedic implants with the purpose of initiating controlled reactions in tissues that surround the implant, is one of the modern approaches in medical materials. A key feature of functional polymers is their ability to form complexes with various metal ions in solution. Chitosan is natural biopolymer with pronounced affinity to transition metal ions. Some researches prove the higher antimicrobial activity of Chitosan-metal complexes compared with pure Chitosan. The purpose of this work was the study of antimicrobial activity of Chitosan nanoparticles modified by metal ions Ag+, Cu2+, Zn2+, Mg2+ against reference strains S. aureus 25923 ATSS, E. coli ATCC 25922, C. albicans ATCC 885653 for their further use as components of the composite biomaterials for medical purpose.Chitosan nanoparticles suspension was prepared by known method based on the ionotropic gelation between chitosan and sodium tripolyphosphate.To obtain Chitosan-metal nanoparticles to the Chitosan suspension were added the corresponding metal ions aqueous solutions in quantity to match the concentration of metal ions of 200 ppm . Antibacterial activities of Ag+, Cu2+, Zn2+, Mg2+ ions doped Chitosan nanoparticles, pure Chitosan nanoparticles, metal ions and 1% (v/v acetic acid solution (it was used as solvent for Chitosan against bacteria were evaluated by determination of minimum inhibitory concentration (MIC and minimum bactericidal concentration (MBC in vitro. Muller– Hinton (MH broth and MH agar (Russia were used as growth media. The bacteria suspension for further use was prepared with concentration that corresponded 0,5units by McFarland scale. The MIC was determined by a broth dilution method. The results were read after 24 hours of experimental tubes incubation at 37 oC as equivalent to the concentration of the tube without visible growth. To evaluate MBC, a sample of 0,1 ml was transferred from

  8. Superconducted tour

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1988-09-15

    Superconductivity - the dramatic drop in electrical resistance in certain materials at very low temperatures - has grown rapidly in importance over the past two or three decades to become a key technology for high energy particle accelerators. It was in this setting that a hundred students and 15 lecturers met in Hamburg in June for a week's course on superconductivity in particle accelerators, organized by the CERN Accelerator School and the nearby DESY Laboratory.

  9. Superconductivity: Phenomenology

    International Nuclear Information System (INIS)

    Falicov, L.M.

    1988-08-01

    This document discusses first the following topics: (a) The superconducting transition temperature; (b) Zero resistivity; (c) The Meissner effect; (d) The isotope effect; (e) Microwave and optical properties; and (f) The superconducting energy gap. Part II of this document investigates the Ginzburg-Landau equations by discussing: (a) The coherence length; (b) The penetration depth; (c) Flux quantization; (d) Magnetic-field dependence of the energy gap; (e) Quantum interference phenomena; and (f) The Josephson effect

  10. Phase diagrams for systems Cu2S-AIIS (AII=Mg, Ca, Sr, Ba)

    International Nuclear Information System (INIS)

    Andreev, O.V.; Sikerina, N.V.; Solov'eva, A.V.

    2005-01-01

    By the methods of physicochemical analysis phase diagrams of Cu 2 S-A II S (A II =Mg, Ca, Sr, Ba) systems are studied. The system Cu 2 S-SrS is of eutectic type with eutectic coordinates 1095 K and 21.5 mol.% of SrS. Solubility of SrS in Cu 2 S is 2 mol.% at 1095 K. Regularities of phase diagram changes of Cu 2 S-A II S (A II =Mg, Ca, Sr, Ba) system are determined. Thermodynamic analysis is done [ru

  11. Ability of Cu2+-montmorillonite to accept an toxic pollutants

    International Nuclear Information System (INIS)

    Janikova, V.; Jona, E.; Janik, R.; Pavlik, V.

    2015-01-01

    It is global problem that toxic pollutants are in the permanent contact to people through soil and water. Nowadays, it is important to eliminate these pollutants for future generations and to keep environment in the health condition. In relation to this article, aromatic organic compounds like benzene, phenol and aniline were chosen. These are used in various branches of industry, mainly in rubber industry or for production of dyes and in addition, phenol is commonly used in cosmetics or in food industry. Montmorillonite is clay mineral consisting of 2:1 sheets (tetrahedral:octahedral) and interlayer space where exchangeable cations and water molecules are present. Due to its structure, montmorillonite is able to accept some compounds or pollutants. This is the reason why it is mainly used as the covering material of radioactive waste in order to remove toxic pollutants. For investigation of toxic pollutants removing, XRD powder diffraction, infrared spectroscopy and thermal analysis were used. Our results show that Cu 2+ -montmorillonite is able to accept toxic benzene ring-based pollutants into interlayer. This mentioned ability can be proven on the basis of the investigation results relating to difference of interlayer distance, typical frequencies of -OH group or -NH 2 group, while these results were supplemented by thermal properties. (authors)

  12. Bose-Einstein condensation of excitons in Cu2O

    International Nuclear Information System (INIS)

    Snoke, D.W.

    1990-01-01

    Free excitons provide the only experimental system other than helium in which the behavior of particles with mass is known to follow Bose-Einstein statistics. Experimental observations are presented of the kinetic energy distribution of excitons in the direct-gap semiconductor Cu 2 O, both the triplet orthoexciton state and the singlet paraexciton state. The density and temperature of the exciton gas closely follow the phase boundary for Bose-Einstein condensation. At the highest densities, the lower-lying paraexcitons take on an anomalous energy distribution with a sharp, high-energy edge. This odd distribution of particle energies may be associated with Bose-Einstein condensation into a state with nonzero momentum. Indeed, the excitons leave the region of their creation at supersonic velocities. In addition to the experimental observations, theoretical models are presented for several aspects of this nonequilibrium system. The equilibration of a nearly-ideal boson gas is modeled, finding that a significant time is required for the approach to condensation. The temperature and density of the excitons in steady state are modeled based on known classical kinetic effects in semiconductors, and the effects of Bose-Einstein statistics on these processes estimated

  13. A jelly-roll process for high temperature superconducting tapes and wires

    International Nuclear Information System (INIS)

    Tsuei, C.C.; Chi, C.C.; Frey, T.; Mitzi, D.B.; Kazyaka, T.; Haugan, T.; Ye, J.; Patel, S.; Shaw, D.T.; Wu, M.K.

    1992-01-01

    As an alternative to the powder-in-tube method, a new technique called the jelly-roll process is proposed for making high-T c superconducting tapes and wires. A normal-metal sheet coated with high-T c cuprate is configured in a jelly-roll fashion and cold worked into tapes or wires made of alternating cuprate superconductor and normal metal layers. The feasibility of this new process is demonstrated for both the YBa 2 Cu 3 O 7 /Ag and Bi 2 Sr 2 CaCu 2 O 8 /Ag composite systems. The role of reduction in the cross-sectional area by cold-rolling, heat treatment and oxygenation in optimizing T c and J c has been studied. Preliminary results indicate that partialmelt texturing, in the Bi 2 Sr 2 CaCu 2 O 8 /Ag system, results in a relatively field independent J c (H c (H = 0) ∝5 X 10 4 A cm -2 at 4.2 K

  14. Effects of cationic substitution on the electronic and magnetic properties of manganocuprate with a layered Eu3Ba2Mn2Cu2O12 structure

    International Nuclear Information System (INIS)

    Matsubara, Ichiro; Funahashi, Ryoji; Ueno, Kazuo; Ishikawa, Hiroshi; Kida, Noriaki; Ohno, Nobuhito

    1998-01-01

    Systematic studies on the effect of substitutions on the layered manganocuprate Eu 3 Ba 2 Mn 2 Cu 2 O 12 have been conducted. To introduce holes, the authors have made substitutions of Ca for Eu and/or Sc for Mn, (Eu 3-x Ca x )Ba 2 (Mn 2-y Sc y )Cu 2 O 12 . Single-phase compounds are obtained over a fairly wide range of x and y values for x ≤ 0.7 (y = 0), x ≤ 0.5 (y = 0.5), and x ≤ 0.1 (y = 1.0). The doped holes are received predominantly at the Mn-O site and change the charge of Mn from 3+ to 4+, and no superconductivity has been obtained for any sample. The electronic ground state of (Eu 3-x Ca x )Ba 2 (Mn 2-y Sc y )Cu 2 O 12 is discussed by comparing with that of the three-dimensional perovskite La 1-x Ca x MnO 3 and K 2 NiF 4 -type La 1-x Sr 1+x MnO 4 compounds. The substitution of Sr for Ba gives rise to a different crystal structure, the Sr 3 Ti 2 O 7 structure

  15. Localization and interaction effects during superconductor-insulator transition of Bi2Sr2Ca1-xGdxCu2O8+d

    International Nuclear Information System (INIS)

    Jayaram, B.; Lanchester, P.C.; Weller, M.T.

    1991-01-01

    An extensive study has been made of the resistivity of superconducting and semiconducting samples of the Bi 2 Sr 2 Ca 1-x Gd x Cu 2 O 8+d system. The effect of changing the Gd concentration and the annealing conditions is found to be a gradual change in the normal-state resistivity measured at 280 K (ρ n ). With the increase in ρ n , T c is depressed. The form of the T c depression is found to be consistent with a theory of localization and interaction effects on the superconductivity. In the insulator regime, however, the resistivity is due to variable-range hopping (VRH), the dimensionality of which changes from two to three as the ρ n increases away from the superconductor-insulator boundary. The observation of the two-dimensional VRH behavior in juxtaposition with the superconductivity is in qualitative agreement with a theoretical model that considers the competition between superconductivity and localization in a disordered system. When ρ n >1 Ω cm, the resistivity variation is found to be dominated by multiphonon-assisted hopping

  16. Nature of the high-binding-energy dip in the low-temperature photoemission spectra of Bi2Sr2CaCu2O8+δ

    International Nuclear Information System (INIS)

    Dessau, D.S.; Shen, Z.; Wells, B.O.; King, D.M.; Spicer, W.E.; Arko, A.J.; Lombardo, L.W.; Mitzi, D.B.; Kapitulnik, A.

    1992-01-01

    At the transition to superconductivity, an anomalous high-binding-energy (∼-90 meV) dip appears in the low-temperature photoemission spectra taken along the Γ-bar M high-symmetry direction of Bi 2 Sr 2 CaCu 2 O 8+δ . This paper details experiments which further characterize the energy and k-space dependence of this dip structure. The dip occurs over a wide portion of the Γ-bar M zone diagonal (110), yet shows minimal energy dispersion. In the spectra taken along the Γ-X zone edge (100), the dip is very weak or not present. We show that these results imply that the dip is not an artifact dependent on the experiment or special features of the band structure and therefore is an intrinsic feature of the superconducting state of Bi 2 Sr 2 CaCu 2 O 8+δ . The behavior of the normal-state bands along Γ-bar M in relation to the local-density-approximation prediction of a Bi-O-based electron ''pocket'' is also discussed, with our data explained most naturally if the Bi-O band remains above the Fermi level for all k

  17. Optoelectronic characterizations of vacuum evaporated Cu 2 SnS 3 ...

    African Journals Online (AJOL)

    ... of non-toxic, cheap earthly abundant, ternary compound of Cu2SnS3 thin film. ... film were investigated by X-Ray Diffraction and Scanning Electron Microscope. ... to determine the electrical properties of the deposited Cu2SnS3 ternary films.

  18. Impacts of EDTA on uptake and accumulation of Cu 2+ by spinach ...

    African Journals Online (AJOL)

    The effects of EDTA on Cu2+ uptake by spinach (spinacia oleracea L) seedlings replanted in hydroponic solutions in a greenhouse were investigated. Four week old seedlings were exposed to various doses of Cu2+ (0, 5, 10, 15, and 20mg/L) and constant concentration of EDTA (10mM). During the exposure, the plant ...

  19. Enhanced catalyst activity by decorating of Au on Ag@Cu2O nanoshell

    Science.gov (United States)

    Chen, Lei; Liu, Maomao; Zhao, Yue; Kou, Qiangwei; Wang, Yaxin; Liu, Yang; Zhang, Yongjun; Yang, Jinghai; Jung, Young Mee

    2018-03-01

    We successfully synthesized Au-decorated Ag@Cu2O heterostructures via a simple galvanic replacement method. As the Au precursor concentration increased, the density of the Au nanoparticles (NPs) on the Ag@Cu2O surface increased, which changed the catalytic activity of the Ag@Cu2O-Au structure. The combination of Au, Ag, and Cu2O exhibited excellent catalytic properties, which can further effect on the catalyst activity of the Ag@Cu2O-Au structure. In addition, the proposed Ag@Cu2O-Au nanocomposite was used to transform the organic, toxic pollutant, 4-nitrophenol (4-NP), into its nontoxic and medicinally important amino derivative via a catalytic reduction to optimize the material performance. The proposed Au-decorated Ag@Cu2O exhibited excellent catalytic activity, and the catalytic reduction time greatly decreased (5 min). Thus, three novel properties of Ag@Cu2O-Au, i.e., charge redistribution and transfer, adsorption, and catalytic reduction of organic pollutants, were ascertained for water remediation. The proposed catalytic properties have potential applications for photocatalysis and localized surface plasmon resonance (LSPR)- and peroxidase-like catalysis.

  20. Growth and characterisation of potentiostatically electrodeposited Cu2O and Cu thin films

    International Nuclear Information System (INIS)

    Wijesundera, R.P.; Hidaka, M.; Koga, K.; Sakai, M.; Siripala, W.

    2006-01-01

    Cuprous oxide and copper thin films were potentiostatically electrodeposited in an acetate bath. Voltammetric curves were used to investigate the growth parameters; deposition potential, pH and temperature of the bath. Deposition potential dependency on the structural, morphological, optical and electronic properties of the films were investigated by the X-ray diffraction measurements, scanning electron micrographs, absorption measurements and dark and light current-voltage characterisations. It was observed that single phase polycrystalline Cu 2 O can be deposited from 0 to - 300 mV Vs saturated calomel electrode (SCE) and co-deposition of Cu and Cu 2 O starts at - 400 mV Vs SCE. Further increase in deposition potential from - 700 mV Vs SCE produces single phase Cu thin films. Single phase polycrystalline Cu 2 O thin films with cubic grains of 1-2 μm can be possible within the very narrow potential domain around - 200 mV Vs SCE. Enhanced photoresponse in a photoelectrochemical cell is produced by the Cu 2 O thin film prepared at - 400 mV Vs SCE, where Cu is co-deposited with Cu 2 O with random distribution of Cu spheres on the Cu 2 O surface. This study reveals that a single deposition bath can be used to deposit both Cu and Cu 2 O separately and an admixture of Cu-Cu 2 O by controlling the deposition parameters

  1. Phytoremediation of heavy metal copper (Cu2+) by sunflower (Helianthus annuus l.)

    Science.gov (United States)

    Mahardika, G.; Rinanti, A.; Fachrul, M. F.

    2018-01-01

    A study in microcosmic condition has been carried out to determine the effectiveness of Helianthus annuus as a hyperaccumulator plant for heavy metal, Copper (Cu2+), that exposed in the soil. Artificial pollutants containing Copper (Cu2+) 0, 60, 120, 180 ppm are exposed to uncontaminated soil. The 12-weeks old H. annuus seedling were grown in Cu2+ contaminated soil, with variations of absorption time 3, 6, and 9 weeks. Analysis of Cu2+ concentration on soil and H. annuus (root, stem, leaf) was analised by Atomic Absorbtion Spectrometry (AAS). H. annuus are capable for Cu2+ removal, and the highest removal of Cu2+ is 85.56%, the highest metal accumulation/bioconcentration factor (BCF) is 0.99 occurred at roots with 9 weeks of exposure time and the highest translocation factor (TF) is 0.71. This highest removal is five times better than absorption by stems and leaves. The results concluded, the use of H. annuus for phytoextraction of heavy metals Cu2+ in contaminated soil can be an alternative to the absorption of heavy metal Cu2+ with low concentration metals which is generally very difficult to do in physical-chemical removal.

  2. Two-dimensional Cu2Si sheet: a promising electrode material for nanoscale electronics

    Science.gov (United States)

    Meng Yam, Kah; Guo, Na; Zhang, Chun

    2018-06-01

    Building electronic devices on top of two-dimensional (2D) materials has recently become one of most interesting topics in nanoelectronics. Finding high-performance 2D electrode materials is one central issue in 2D nanoelectronics. In the current study, based on first-principles calculations, we compare the electronic and transport properties of two nanoscale devices. One device consists of two single-atom-thick planar Cu2Si electrodes, and a nickel phthalocyanine (NiPc) molecule in the middle. The other device is made of often-used graphene electrodes and a NiPc molecule. Planer Cu2Si is a new type of 2D material that was recently predicted to exist and be stable under room temperature [11]. We found that at low bias voltages, the electric current through the Cu2Si–NiPc–Cu2Si junction is about three orders higher than that through graphene–NiPc–graphene. Detailed analysis shows that the surprisingly high conductivity of Cu2Si–NiPc–Cu2Si originates from the mixing of the Cu2Si state near Fermi energy and the highest occupied molecular orbital of NiPc. These results suggest that 2D Cu2Si may be an excellent candidate for electrode materials for future nanoscale devices.

  3. Cu2+ and Ca2+ adsorption to goethite in the presence of fulvic acids

    NARCIS (Netherlands)

    Weng, L.P.; Riemsdijk, van W.H.; Hiemstra, T.

    2008-01-01

    The interaction between copper ions (Cu2+), Strichen fulvic acid (FA), and goethite has been studied with batch experiments in the pH range of 3¿11. Similar systems with Ca2+ have been studied previously and are used here for comparison. Depending on the pH and Cu2+ loading, the binding of Cu ions

  4. An Amidochlorin-Based Colorimetric Fluorescent Probe for Selective Cu2+ Detection

    Directory of Open Access Journals (Sweden)

    Wenting Li

    2016-01-01

    Full Text Available The design and synthesis of selective and sensitive chemosensors for the quantification of environmentally and biologically important ionic species has attracted widespread attention. Amidochlorin p6 (ACP; an effective colorimetric and fluorescent probe for copper ions (Cu2+ in aqueous solution derived from methyl pheophorbide-a (MPa was designed and synthesized. A remarkable color change from pale yellow to blue was easily observed by the naked eye upon addition of Cu2+; and a fluorescence quenching was also determined. The research of fluorescent quenching of ACP-Cu2+ complexation showed the detection limit was 7.5 × 10−8 mol/L; which suggested that ACP can act as a high sensitive probe for Cu2+ and can be used to quantitatively detect low levels of Cu2+ in aqueous solution. In aqueous solution the probe exhibits excellent selectivity and sensitivity toward Cu2+ ions over other metal ions (M = Zn2+; Ni2+; Ba2+; Ag+; Co2+; Na+; K+; Mg2+; Cd2+; Pb2+; Mn2+; Fe3+; and Ca2+. The obvious change from pale yellow to blue upon the addition of Cu2+ could make it a suitable “naked eye” indicator for Cu2+.

  5. Magnetic, electrical and structural properties of the Re-doped ruthenocuprate Ru1−xRexSr2GdCu2Oy

    International Nuclear Information System (INIS)

    Corredor, L.T.; Albino Aguiar, J.; Landínez Téllez, D.A.; Pureur, P.; Mesquita, F.; Roa-Rojas, J.

    2015-01-01

    Highlights: • We investigated the effect of the dilution of magnetic Ru sub-lattice of RuSr 2 GdCu 2 O 8 . • We synthesized the doped compound Rui x Re x Sr 2 GdCu 2 O y , for 3%, 6%, 9% and 12% Re. • Re would affect the electron coupling: just 3 and 6% samples were superconductor. • Superconductivity emergence strongly affects magnetic properties of 3 and 6% samples. • A weak ferromagnetic component is consistent with a globally antiferromagnetic system. - Abstract: Despite the discovery of new superconductors classes, high-Tc oxides continue to be a current topic, because of their complex phase diagrams and doping-dependant effects (allowing one to investigate the interaction between orbitals), as well as structural properties such as lattice distortion and charge ordering, among many others. Ruthenocuprates are magnetic superconductors in which the magnetic transition temperature is much higher than the critical superconducting temperature, making them unique compounds. With the aim of investigating the dilution of the magnetic Ru sub-lattice, we proposed the synthesis of the Ru 1−x Re x Sr 2 GdCu 2 O y ruthenocuprate-type family, adapting the known two-step process (double perovskite + CuO) by directly doping the double perovskite, thus obtaining the perovskite compound Sr 2 GdRu 1−x Re x O y , which represents a new synthesis process to the best of our knowledge. Our samples were structurally characterized through X-ray diffraction, and the patterns were analysed via Rietveld refinement. A complete magnetic characterization as a function of temperature and applied field, as well as transport measurements were carried out. We discuss our results in the light of the two-lattice model for ruthenocuprates, and a relation between RuO 2 (magnetic) and CuO 2 (superconductor) sub-lattices can clearly be observed

  6. Synthesis and characterization of Cu2O/TiO2 photocatalysts for H2 evolution from aqueous solution with different scavengers

    Science.gov (United States)

    Li, Yanping; Wang, Baowei; Liu, Sihan; Duan, Xiaofei; Hu, Zongyuan

    2015-01-01

    A series of Cu2O/TiO2 photocatalysts with different molar fraction of Cu2O were prepared by a facile modified ethanol-induced approach followed by a calcination process. The chemical state of copper compound was proved to be cuprous oxide by the characterization of X-ray photoelectron spectra (XPS). Furthermore, these composite oxides were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption desorption and UV-vis techniques to study the morphologies, structures, and optical properties of the as-prepared samples. The results indicated that the photocatalytic activity of n-type TiO2 was significantly enhanced by combined with p-type Cu2O, due to the efficient p-n heterojunction. The p-n heterojunction between Cu2O and TiO2 can enhance visible-light adsorption, efficiently suppress charge recombination, improve interfacial charge transfer, and especially provide plentiful reaction active sites on the surface of photocatalyst. As a consequence, the prepared 2.5-Cu2O/TiO2 photocatalyst exhibited the highest photocatalytic activity for H2 evolution rate and reached 2048.25 μmol/(g h), which is 14.48 times larger than that of pure P25. The apparent quantum yield (AQY) of the 2.5-Cu2O/TiO2 sample at 365 nm was estimated to be 4.32%. In addition, the influence of different scavengers, namely methanol, anhydrous ethanol, ethylene glycol and glycerol, on the photocatalytic activity for H2 evolution rate was discussed.

  7. Study of heat conductivity, electric conductivity and thermo-emf of BiSrCaCu2Ox and Bi1.82Sr1.73Ca1.73Ca1.25Cu2.2Ox systems

    International Nuclear Information System (INIS)

    Zhukova, T.B.; Parfen'eva, L.S.; Popov, V.V.; Melekh, B.T.; Smirnov, I.A.; Khalmedov, Kh.M.

    1991-01-01

    Phase compositions are determined and temperature dependences are measured of x-heat conductivity, ρ-electric resistance and α-thermo-emf of polycrystal, monophase, highly textured HTSC samples of BiSrCaCu 2 O x and Bi 1.82 Sr 1.73 Ca 1.25 Cu 2.2 O x produced through method of direct induction melting in the air in a cold container. Sample 'aging' after storage in the air and vacuum, leading to decrease in the number of foring phases and increase in the basic phase content as well as to change of x, ρ and α coefficients is identified

  8. Research on Cu2ZnSnTe4 crystals and heterojunctions based on such crystals

    Directory of Open Access Journals (Sweden)

    Kovaliuk T. T.

    2015-12-01

    Full Text Available The paper reports on the results of the studies of magnetic, kinetic and optical properties of Cu2ZnSnTe4 crystals. The Cu2ZnSnTe4 crystals showed diamagnetic properties (the magnetic susceptibility almost independent of the magnetic field and temperature. The Cu2ZnSnTe4 crystals possessed p-type of conductivity and the Hall coefficient was independent on temperature. The temperature dependence of the electrical conductivity of the Cu2ZnSnTe4 crystal shows metallic character, i. e. decreases with the increase of temperature, that is caused by the lower charge carrier mobility at higher temperature. Thermoelectric power of the samples ispositive that also indicates on the prevalence of p-type conductivity. Heterojunctions n-TiN/p-Cu2ZnSnTe4, n-TiO2/p-Cu2ZnSnTe4 and n-MoO/p-Cu2ZnSnTe4 were fabricated by the reactive magnetron sputtering of TiN, TiO2 and MoOx thin films, respectively, onto the substrates made of the Cu2ZnSnTe4 crystals. The dominating current transport mechanisms in the n-TiN/p-Cu2ZnSnTe4 and n-TiO2/p-Cu2ZnSnTe4 heterojunctions were established to be the tunnel-recombination mechanism at forward bias and tunneling at reverse bias.

  9. Bimetallic AgCu/Cu2O hybrid for the synergetic adsorption of iodide from solution.

    Science.gov (United States)

    Mao, Ping; Liu, Ying; Liu, Xiaodong; Wang, Yuechan; Liang, Jie; Zhou, Qihang; Dai, Yuexuan; Jiao, Yan; Chen, Shouwen; Yang, Yi

    2017-08-01

    To further improve the capacity of Cu 2 O to absorb I - anions from solution, and to understand the difference between the adsorption mechanisms of Ag/Cu 2 O and Cu/Cu 2 O adsorbents, bimetallic AgCu was doped into Cu 2 O through a facile solvothermal route. Samples were characterized and employed to adsorb I - anions under different experimental conditions. The results show that the Cu content can be tuned by adding different volumes of Ag sols. After doping bimetallic AgCu, the adsorption capacity of the samples can be increased from 0.02 mmol g -1 to 0.52 mmol g -1 . Moreover, the optimal adsorption is reached within only 240 min. Meanwhile, the difference between the adsorption mechanisms of Ag/Cu 2 O and Cu/Cu 2 O adsorbents was verified, and the cooperative adsorption mechanism of the AgCu/Cu 2 O hybrid was proposed and verified. In addition, the AgCu/Cu 2 O hybrid showed excellent selectivity, e.g., its adsorption efficiencies are 85.1%, 81.9%, 85.9% and 85.7% in the presence of the Cl - , CO 3 2- , SO 4 2- and NO 3 - competitive anions, respectively. Furthermore, the AgCu/Cu 2 O hybrid can worked well in other harsh environments (e.g., acidic, alkaline and seawater environments). Therefore, this study is expected to promote the development of Cu 2 O into a highly efficient adsorbent for the removal of iodide from solution. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Superconducting cyclotrons

    International Nuclear Information System (INIS)

    Blosser, H.G.; Johnson, D.A.; Burleigh, R.J.

    1976-01-01

    Superconducting cyclotrons are particularly appropriate for acceleration of heavy ions. A review is given of design features of a superconducting cyclotron with energy 440 (Q 2 /A) MeV. A strong magnetic field (4.6 tesla average) leads to small physical size (extraction radius 65 cm) and low construction costs. Operating costs are also low. The design is based on established technology (from present cyclotrons and from large bubble chambers). Two laboratories (in Chalk River, Canada and in East Lansing, Michigan) are proceeding with construction of full-scale prototype components for such cyclotrons

  11. Ac superconducting articles and a method for their manufacture

    International Nuclear Information System (INIS)

    Meyerhoff, R.W.

    1975-01-01

    A novel ac superconducting article is described comprising a composite structure having a superconducting surface along with a high thermally conductive material wherein the superconducting surface has the desired physical properties, geometrical shape and surface finish produced by the steps of depositing a superconducting layer upon a substrate having a predetermined surface finish and shape which conforms to that of the desired superconducting article, depositing a supporting layer of material on the superconducting layer and removing the substrate, the surface of the superconductor being a replica of the substrate surface. (auth)

  12. Superconducting materials arrangement and realization process

    International Nuclear Information System (INIS)

    Pribat, D.; Dieumegard, D.; Garry, G.; Mercandalli, L.

    1989-01-01

    Thin and stable layers of the superconducting oxychloride YBa Cu OF with an accurate content of oxygen and fluorine can be obtained by the invention. The superconducting material is deposited on a substrate and encapsulated in an ionic conductor for adjustment of stoichiometry. Composition of the superconductor can be adjusted by electrolysis [fr

  13. Oxide superconducting ribbon and its fabrication process

    International Nuclear Information System (INIS)

    Belouet, C.

    1990-01-01

    A film without cavities, of perovskite type superconducting oxide is deposited by melting on a metal or composite flexible substrate with a rectangular cross section. The film thickness is comprised between 1 and 100 micrometers and orientation of C axis of superconducting crystals is perpendicular to the subtrate [fr

  14. Accelerators and superconductivity: A marriage of convenience

    International Nuclear Information System (INIS)

    Wilson, M.

    1987-01-01

    This lecture deals with the relationship between accelerator technology in high-energy-physics laboratories and the development of superconductors. It concentrates on synchrotron magnets, showing how their special requirements have brought about significant advances in the technology, particularly the development of filamentary superconducting composites. Such developments have made large superconducting accelerators an actuality: the Tevatron in routine operation, the Hadron Electron Ring Accelerator (HERA) under construction, and the Superconducting Super Collider (SSC) and Large Hadron Collider (LHC) at the conceptual design stage. Other applications of superconductivity have also been facilitated - for example medical imaging and small accelerators for industrial and medical use. (orig.)

  15. Superconducting energy storage magnet

    International Nuclear Information System (INIS)

    Eyssa, Y.M.; Boom, R.W.; Young, W.C.; McIntosh, G.E.; Abdelsalam, M.K.

    1986-01-01

    A superconducting magnet is described comprising: (a) a first, outer coil of one layer of conductor including at least a superconducting composite material; (b) a second, inner coil of one layer of conductor including at least a superconducting composite material. The second coil disposed adjacent to the first coil with each turn of the second inner coil at substantially the same level as a turn on the first coil; (c) an inner support structure between the first and second coils and engaged to the conductors thereof, including support rails associated with each turn of conductor in each coil and in contact therewith along its length at positions on the inwardly facing periphery of the conductor. The rail associated with each conductor is electrically isolated from other rails in the inner support structure. The magnetic field produced by a current flowing in the same direction through the conductors of the first and second coils produces a force on the conductors that are directed inwardly toward the inner support structure

  16. Superconducting materials

    International Nuclear Information System (INIS)

    Ruvalds, J.

    1990-01-01

    This report discusses the following topics: Fermi liquid nesting in high temperature superconductors; optical properties of high temperature superconductors; Hall effect in superconducting La 2-x Sr x CuO 4 ; source of high transition temperatures; and prospects for new superconductors

  17. Superconducting transformer

    International Nuclear Information System (INIS)

    Murphy, J.H.

    1982-01-01

    A superconducting transformer having a winding arrangement that provides for current limitation when subjected to a current transient as well as more efficient utilization of radial spacing and winding insulation. Structural innovations disclosed include compressed conical shaped winding layers and a resistive matrix to promote rapid switching of current between parallel windings

  18. Superconducting magnets

    International Nuclear Information System (INIS)

    1994-08-01

    This report discusses the following topics on superconducting magnets: D19B and -C: The next steps for a record-setting magnet; D20: The push beyond 10 T: Beyond D20: Speculations on the 16-T regime; other advanced magnets for accelerators; spinoff applications; APC materials development; cable and cabling-machine development; and high-T c superconductor at low temperature

  19. Superconducting magnets

    International Nuclear Information System (INIS)

    Willen, E.

    1996-01-01

    Superconducting dipole magnets for high energy colliders are discussed. As an example, the magnets recently built for the Relativistic Heavy Ion Collider at Brookhaven are reviewed. Their technical performance and the cost for the industry-built production dipoles are given. The cost data is generalized in order to extrapolate the cost of magnets for a new machine

  20. Bipolar superconductivity

    International Nuclear Information System (INIS)

    Pankratov, S.G.

    1987-01-01

    A model of bipolaron superconductivity suggested by Soviet scientist Alexandrov A.S. and French scientist Ranninger is presentes in a popular way. It is noted that the bipolaron theory gives a good explanation of certain properties of new superconductors, high critical temperature, in particular

  1. Superconducting transistor

    International Nuclear Information System (INIS)

    Gray, K.E.

    1978-01-01

    A three film superconducting tunneling device, analogous to a semiconductor transistor, is presented, including a theoretical description and experimental results showing a current gain of four. Much larger current gains are shown to be feasible. Such a development is particularly interesting because of its novelty and the striking analogies with the semiconductor junction transistor

  2. Electrical and optical properties of TCO-Cu2O heterojunction devices

    International Nuclear Information System (INIS)

    Tanaka, Hideki; Shimakawa, Takahiro; Miyata, Toshihiro; Sato, Hirotoshi; Minami, Tadatsugu

    2004-01-01

    This report describes the electrical and photovoltaic properties in heterojunction devices consisting of a cuprous oxide (Cu 2 O) sheet and a transparent conducting oxide (TCO) thin film, such as In 2 O 3 , ZnO, In 2 O 3 :Sn (ITO), ZnO:Al (AZO) or AZO-ITO (AZITO) multicomponent oxide, prepared by pulsed laser deposition (PLD). Undoped In 2 O 3 -Cu 2 O heterojunctions prepared by PLD exhibited ohmic current-voltage (I-V) characteristics. The ZnO-Cu 2 O and AZO-Cu 2 O devices exhibited better rectifying I-V characteristics and photovoltaic properties than the ITO-Cu 2 O devices. It was found that the obtainable I-V characteristics and photovoltaic properties were considerably affected by the TCO film deposition conditions. An open-circuit voltage (V OC ) of 0.4 V, a short-circuit current density (J SC ) of 7.1 mA/cm 2 , a fill factor (F.F.) of 0.4 and an energy conversion efficiency (η) of 1.2% were obtained in an AZO-Cu 2 O device under AM2 solar illumination. The V OC , J SC , F.F. and η obtained in AZITO-Cu 2 O heterojunctions increased as the Zn/(Zn+In) atomic ratio was increased

  3. Defects controlling electrical and optical properties of electrodeposited Bi doped Cu2O

    Science.gov (United States)

    Brandt, Iuri S.; Tumelero, Milton A.; Martins, Cesar A.; Plá Cid, Cristiani C.; Faccio, Ricardo; Pasa, André A.

    2018-04-01

    Doping leading to low electrical resistivity in electrodeposited thin films of Cu2O is a straightforward requirement for the construction of efficient electronic and energy devices. Here, Bi (7 at. %) doped Cu2O layers were deposited electrochemically onto Si(100) single-crystal substrates from aqueous solutions containing bismuth nitrate and cupric sulfate. X-ray photoelectron spectroscopy shows that Bi ions in a Cu2O lattice have an oxidation valence of 3+ and glancing angle X-ray diffraction measurements indicated no presence of secondary phases. The reduction in the electrical resistivity from undoped to Bi-doped Cu2O is of 4 and 2 orders of magnitude for electrical measurements at 230 and 300 K, respectively. From variations in the lattice parameter and the refractive index, the electrical resistivity decrease is addressed to an increase in the density of Cu vacancies. Density functional theory (DFT) calculations supported the experimental findings. The DFT results showed that in a 6% Bi doped Cu2O cell, the formation of Cu vacancies is more favorable than in an undoped Cu2O one. Moreover, from DFT data was observed that there is an increase (decrease) of the Cu2O band gap (activation energy) for 6% Bi doping, which is consistent with the experimental results.

  4. Stability enhancement of Cu2S against Cu vacancy formation by Ag alloying

    Science.gov (United States)

    Barman, Sajib K.; Huda, Muhammad N.

    2018-04-01

    As a potential solar absorber material, Cu2S has proved its importance in the field of renewable energy. However, almost all the known minerals of Cu2S suffer from spontaneous Cu vacancy formation in the structure. The Cu vacancy formation causes the structure to possess very high p-type doping that leads the material to behave as a degenerate semiconductor. This vacancy formation tendency is a major obstacle for this material in this regard. A relatively new predicted phase of Cu2S which has an acanthite-like structure was found to be preferable than the well-known low chalcocite Cu2S. However, the Cu-vacancy formation tendency in this phase remained similar. We have found that alloying silver with this structure can help to reduce Cu vacancy formation tendency without altering its electronic property. The band gap of silver alloyed structure is higher than pristine acanthite Cu2S. In addition, Cu diffusion in the structure can be reduced with Ag doped in Cu sites. In this study, a systematic approach is presented within the density functional theory framework to study Cu vacancy formation tendency and diffusion in silver alloyed acanthite Cu2S, and proposed a possible route to stabilize Cu2S against Cu vacancy formations by alloying it with Ag.

  5. PVD of copper sulfide (Cu2S) for PIN-structured solar cells

    International Nuclear Information System (INIS)

    Siol, Sebastian; Brötz, Joachim; Klein, Andreas; Jaegermann, Wolfram; Sträter, Hendrik; Brüggemann, Rudolf; Bauer, Gottfried H

    2013-01-01

    Thin layers of chalcocite (Cu 2 S) have been deposited via physical vapour deposition using various pre- and post-treatment parameters. The electrical and morphological properties have been investigated by in situ XPS, SEM and XRD measurements. Calibrated photoluminescence experiments were performed to investigate the material's suitability as an absorber layer in thin-film solar cells. Measurements of annealed Cu 2 S layers on glass without any surface passivation showed an optical band gap of 1.25 eV as well as a splitting of the quasi-Fermi levels of 710 meV. This value exceeds the highest reported open-circuit voltage for Cu 2 S-based devices so far, which leads to the assumption that Cu 2 S has not been brought to its full potential yet. The band alignments for ZnO/Cu 2 S as well as Cu 2 S/Cu 2 O interfaces have been determined using in situ XPS interface experiments to suggest a novel device structure according to the favourable PIN-layout. First devices have been built, but show no efficiency due to shunting caused by the inferior morphology of the absorber layers. (paper)

  6. Growth of Cu2ZnSnS4(CZTS) by Pulsed Laser Deposition for Thin film Photovoltaic Absorber Material

    Science.gov (United States)

    Nandur, Abhishek; White, Bruce

    2014-03-01

    CZTS (Cu2ZnSnS4) has become the subject of intense interest because it is an ideal candidate absorber material for thin-film solar cells with an optimal band gap (1.5 eV), high absorption coefficient (104 cm-1) and abundant elemental components. Pulsed Laser Deposition (PLD) provides excellent control over film composition since thin films are deposited under high vacuum with excellent stoichiometry transfer from the target. CZTS thin films were deposited using PLD from a stoichiometrically close CZTS target (Cu2.6Zn1.1Sn0.7S3.44). The effects of laser energy fluence and substrate temperature and post-deposition sulfur annealing on the surface morphology, composition and optical absorption have been investigated. Optimal CZTS thin films exhibited a band gap of 1.54 eV with an absorption coefficient of 4x104cm-1. A solar cell utilizing PLD grown CZTS with the structure SLG/Mo/CZTS/CdS/ZnO/ITO showed a conversion efficiency of 5.85% with Voc = 376 mV, Jsc = 38.9 mA/cm2 and Fill Factor, FF = 0.40.

  7. Photoelectrochemical oxidation of ibuprofen via Cu_2O-doped TiO_2 nanotube arrays

    International Nuclear Information System (INIS)

    Sun, Qiannan; Peng, Yen-Ping; Chen, Hanlin; Chang, Ken-Lin; Qiu, Yang-Neng; Lai, Shiau-Wu

    2016-01-01

    Highlights: • A p–n junction material was synthesized to enhance photocatalytic ability. • Cu_2O-doped TiO_2 nanotube arrays works as a photoanode in a PEC system. • Recombination of photo-generated holes and electrons were greatly reduced. • Synergetic effect was quantified in PEC degradation. • Recombination of photogenerated holes and electrons was greatly enhanced. - Abstract: A p–n junction based Cu_2O-doped TiO_2 nanotube arrays (Cu_2O-TNAs) were synthesized and used as a working anode in a photoelectrochemical (PEC) system. The results revealed that the Cu_2O-TNAs were dominated by the anatase phase and responded significantly to visible light. XPS analyses indicated that with an amount of 24.79% Cu doping into the structure, the band gap of Cu_2O-TNAs was greatly reduced. SEM images revealed that the supported TiO_2 nanotubes had diameters of approximately 80 nm and lengths of about 2.63 μm. Upon doping with Cu_2O, the TiO_2 nanotubes maintained their structural integrity, exhibiting no significant morphological change, favoring PEC applications. Under illumination, the photocurrent from Cu_2O/TNAs was 2.4 times larger than that from TNAs, implying that doping with Cu_2O significantly improved electron mobility by reducing the rate of recombination of electron-hole pairs. The EIS and Bode plot revealed that the estimated electron lifetimes, τ_e_l, of TNAs and Cu_2O/TNAs were 6.91 and 26.26 ms, respectively. The efficiencies of degradation of Ibuprofen by photoelectrochemical, photocatalytic (PC), electrochemical (EC) and photolytic (P) methods were measured.

  8. Ultrasensitive colorimetric detection of Cu2+ ion based on catalytic oxidation of L-cysteine.

    Science.gov (United States)

    Yin, Kun; Li, Bowei; Wang, Xiaochun; Zhang, Weiwei; Chen, Lingxin

    2015-02-15

    As an essential element, copper ion (Cu(2+)) plays important roles in human beings for its participation in diverse metabolic processes as a cofactor and/or a structural component of enzymes. However, excessive uptake of Cu(2+) ion gives rise to the risk of certain diseases. So, it is important to develop simple ways to monitor and detect Cu(2+) ion. In this study, a simple, facile colorimetric sensor for the ultrasensitive determination of Cu(2+) ion was developed based on the following principle: L-cysteine and 1-chloro-2,4-dinitrobenzene (CDNB) could be conjugated to form the yellow product 2,4-dinitrophenylcysteine (DNPC), which was measurable at 355nm; however, upon addition of Cu(2+) ion, the absorbance of DNPC would be decreased owing to the Cu(2+) ion catalytic oxidation of L-cysteine to L-cystine in the presence of O2. Thus, the colorimetric detection of Cu(2+) ion could be achieved. The optimal pH, buffer, temperature and incubation time for the colorimetric sensor were obtained of pH 6.8 in 0.1M HEPES solution, 90 °C and 50 min, respectively. A good linearity within the range of 0.8-10 nM (r = 0.996) was attained, with a high detectability up to 0.5nM. Analyses of Cu(2+) ion in drinking water, lake water, seawater and biological samples were carried out and the method performances were found to agree well with that obtained by ICP-MS. The developed simple colorimetric sensor proved applicable for Cu(2+) ion determination in real samples with high sensitivity and selectivity. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Antimicrobial activity and biocompatibility of Ag+- and Cu2+-doped biphasic hydroxyapatite/α-tricalcium phosphate obtained from hydrothermally synthesized Ag+- and Cu2+-doped hydroxyapatite

    International Nuclear Information System (INIS)

    Radovanović, Željko; Jokić, Bojan; Veljović, Djordje; Dimitrijević, Suzana; Kojić, Vesna; Petrović, Rada; Janaćković, Djordje

    2014-01-01

    Hydroxyapatite (HAp) powders doped with Ag + or Cu 2+ were synthesized by a hydrothermal method in order to obtain biomaterial with an antimicrobial effect. The synthesis was performed with two contents of dopant (Ag + or Cu 2+ ) by considering both the antimicrobial activities and biocompatibility of the powders. The doped HAp was annealed at 1200 °C for 2 h with the intention of investigating the influence of doping with Ag + and Cu 2+ on the creation of the biphasic HAp/α-tricalcium phosphate (HAp/α-TCP) and determining the antimicrobial activity and biocompatibility of the obtained biphasic powders. Analyses of all powders, undoped and doped HAp and HAp/α-TCP, were performed by Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), atomic absorption spectroscopy (AAS) and energy-dispersive X-ray spectroscopy (EDS). The in vitro antibacterial activities of the powders were evaluated against: Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. All powders showed good antimicrobial activity but generally the powders of doped HAp/α-TCP had more uniform results against all pathogenic microorganisms than the powders of doped HAp. In vitro biocompatibility tests, MTT and DET, were used to evaluate the biocompatibility of Ag + - and Cu 2+ -doped HAp/α-TCP with MRC-5 human fibroblast cells. These tests confirmed that powders do not have a cytotoxic effect. The HAp/α-TCP powders doped with the lower content of Ag + and Cu 2+ showed especially good biocompatibility. Antimicrobial and biocompatibility tests recommend the Ag + - and Cu 2+ -doped HAp/α-TCP as promising material for use in reconstructive surgery of bone.

  10. Appearance of ferroelectricity by suppressing superconductivity in nanoparticle dispersed glassy precursor for high Tc superconductor

    International Nuclear Information System (INIS)

    Mukherjee, Soma; Chaudhuri, B.K.; Sakata, H.

    2003-01-01

    The multicomponent Bi 1.8 Pb 0.3 Sr 2 Ca 2 Cu 2.8 K 0.2 O δ (FG) glass is found to show ferroelectric (FE) transition around T fc = 530K. Microstructural (TEM) studies of these glasses indicated the presence of nano-crystalline particles/ clusters (∼10-30 nm size). In this glass-nanoparticle composite (GNC), presence of ferroelectric nano-particles/ islands is considered to be responsible for the FE behavior. The K-free FG type glasses showing no dielectric anomaly (or ferroelectricity) are precursors of high T c superconductors which become superconductors (T c ∼80K) by annealing around 840 degC. The K-doped (FG) GNC is, however, not superconducting in the corresponding annealed phase which indicates suppression of superconductivity due to the presence of K or by the appearance of ferroelectricity. Transport and dielectric properties of both K doped and undoped GNC have been studied and they are found to be semiconducting and follow non-adiabatic small polaron hopping conduction mechanism. (author)

  11. Theory of superconductivity

    International Nuclear Information System (INIS)

    Crisan, M.

    1988-01-01

    This book discusses the most important aspects of the theory. The phenomenological model is followed by the microscopic theory of superconductivity, in which modern formalism of the many-body theory is used to treat most important problems such as superconducting alloys, coexistence of superconductivity with the magnetic order, and superconductivity in quasi-one-dimensional systems. It concludes with a discussion on models for exotic and high temperature superconductivity. Its main aim is to review, as complete as possible, the theory of superconductivity from classical models and methods up to the 1987 results on high temperature superconductivity. Contents: Phenomenological Theory of Superconductivity; Microscopic Theory of Superconductivity; Theory of Superconducting Alloys; Superconductors in a Magnetic Field; Superconductivity and Magnetic Order; Superconductivity in Quasi-One-Dimensional Systems; and Non-Conventional Superconductivity

  12. Theoretical explanation of EPR parameters for Cu2+ ion in TiO2 crystal

    International Nuclear Information System (INIS)

    Dong, H.N.; Wu, S.Y.; Li, P.

    2004-01-01

    The EPR parameters anisotropic g-factors g x , g y and g z for Cu 2+ ion and hyperfine structure constants A x , A y and A z for 63 Cu 2+ and 65 Cu 2+ isotopes in rutile (TiO 2 ) crystal are calculated by the method of diagonalizing the full Hamiltonian matrix. The crystal-field parameters contact with the crystal structure by the aid of the superposition model. The calculated results are in reasonable agreement with the observed values. The results are discussed. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. A Dansyl-Rhodamine Based Fluorescent Probe for Detection of Hg2+ and Cu2.

    Science.gov (United States)

    Yuan, Shizhuang; Su, Wei; Wang, Enju

    2017-09-01

    A novel fluorescent probe based on dansyl-appended rhodamine B was developed. The probe can selectively recognize and sense Hg2+ and Cu2+ from other common metal ions by showing unique fluorescence and absorption characteristics. In MeCN/HEPES buffer solution, the probe gives a ratiometric fluorescent response to Hg2+, which was ascribed to the fluorescence resonance energy transfer from dansyl moiety to the ring-opened rhodamine B moiety, while the presence of Cu2+ causes fluorescence quenching. Beside the fluorescence change, the presence of Cu2+ and Hg2+ can induce intensive absorption at about 555 nm, which resulted in a color change from colorless to pink.

  14. Superconducting properties, chemical compositions, and lattice parameters of Pb-, Sn- and (Pb1-xSnx)Mo6S8

    International Nuclear Information System (INIS)

    Sadakata, N.; Corderman, R.; Asano, T.; Cox, D.; Suenaga, M.; Foner, S.; McNiff, E.J. Jr.

    1991-01-01

    The values of critical temperatures for alloys of Pb- and SnMo 6 S 8 were shown to be lower than those of the respective pure Chevrel phases. Chemical compositional analysis of the compounds revealed that the decreased T c in the alloys are due to the off-stoichiometric compositions in the alloys. Although alloying slightly increased the values of the upper critical field H c2 over that for PbMo 6 S 8 , the H c2 values for these specimens were substantially lower than those which have been reported for PbMo 6 S 8 . Possible causes for these depressed values of H c2 are discussed

  15. Effect of thermal annealing in vacuum on the photovoltaic properties of electrodeposited Cu2O-absorber solar cell

    Directory of Open Access Journals (Sweden)

    Dimopoulos T.

    2014-07-01

    Full Text Available Heterojunction solar cells were fabricated by electrochemical deposition of p-type, cuprous oxide (Cu2O absorber on sputtered, n-type ZnO layer. X-ray diffraction measurements revealed that the as-deposited absorber consists mainly of Cu2O, but appreciable amounts of metallic Cu and cupric oxide (CuO are also present. These undesired oxidation states are incorporated during the deposition process and have a detrimental effect on the photovoltaic properties of the cells. The open circuit voltage (VOC, short circuit current density (jSC, fill factor (FF and power conversion efficiency (η of the as-deposited cells are 0.37 V, 3.71 mA/cm2, 35.7% and 0.49%, respectively, under AM1.5G illumination. We show that by thermal annealing in vacuum, at temperatures up to 300 °C, compositional purity of the Cu2O absorber could be obtained. A general improvement of the heterojunction and bulk materials quality is observed, reflected upon the smallest influence of the shunt and series resistance on the transport properties of the cells in dark and under illumination. Independent of the annealing temperature, transport is dominated by the space-charge layer generation-recombination current. After annealing at 300 °C the solar cell parameters could be significantly improved to the values of: VOC = 0.505 V, jSC = 4.67 mA/cm2, FF = 47.1% and η = 1.12%.

  16. Microstructure and tribological properties of TiCu2Al intermetallic compound coating

    International Nuclear Information System (INIS)

    Guo Chun; Zhou Jiansong; Zhao Jierong; Wang Linqian; Yu Youjun; Chen Jianmin; Zhou Huidi

    2011-01-01

    TiCu 2 Al ternary intermetallic compound coating has been in situ synthesized successfully on pure Ti substrate by laser cladding. Tribological properties of the prepared TiCu 2 Al intermetallic compound coating were systematically evaluated. It was found that the friction coefficient and wear rate was closely related to the normal load and sliding speed, i.e., the friction coefficient of the prepared TiCu 2 Al intermetallic compound coating decreased with increasing normal load and sliding speed. The wear rate of the TiCu 2 Al intermetallic compound coating decreased rapidly with increasing sliding speed, while the wear rate first increased and then decreased at normal load from 5 to 15 N.

  17. Tuning the thermoelectric properties by manipulating copper in Cu2SnSe3 system

    DEFF Research Database (Denmark)

    Prasad K, Shyam; Rao, Ashok; Christopher, Benedict

    2018-01-01

    Cu2+xSnSe3 (0 ≤ x ≤ 0.08) compounds were synthesized by conventional solid-state reaction followed by spark plasma sintering (SPS) technique. Transport properties of the samples were measured as a function of temperature in the temperature range 323–773 K. As compared to Cu2SnSe3 sample, the elec......Cu2+xSnSe3 (0 ≤ x ≤ 0.08) compounds were synthesized by conventional solid-state reaction followed by spark plasma sintering (SPS) technique. Transport properties of the samples were measured as a function of temperature in the temperature range 323–773 K. As compared to Cu2SnSe3 sample...

  18. Synthesis of a Cu2+-Selective Probe Derived from Rhodamine and Its Application in Cell Imaging

    Directory of Open Access Journals (Sweden)

    Chunwei Yu

    2014-11-01

    Full Text Available A new fluorescent probe P based on rhodamine for Cu2+ was synthesized and characterized. The new probe P showed high selectivity to Cu2+ over other tested metal ions. With optimal conditions, the proposed probe P worked in a wide linear range of 1.0 × 10−6–1.0 × 10−5 M with a detection limit of 3.3 × 10−7 M Cu2+ in ethanol-water solution (9:1, v:v, 20 mM HEPES, pH 7.0. Furthermore, it has been used for imaging of Cu2+ in living cells with satisfying results.

  19. Optical and EPR studies of barium alumino borate glasses containing Cu2+ ions

    Science.gov (United States)

    Ahmed, Mohamad Raheem; Phani, A. V. Lalitha; Narsimha Chary, M.; Shareefuddin, Md.

    2018-05-01

    Glass containing Cu2+ ions in (30-x) BaO-xAl2O3-69.5B2O3-0.5CuO (0 ≤ x ≤ 15 mol %) were prepared by the conventional melt quenching technique. Peak free X-ray diffractograms confirmed the amorphous nature of the glass samples. Spectroscopic studies such as optical absorption, EPR were studied to understand the effect of modifier oxide and CuO dopant. From EPR spectra the spin-Hamiltonian parameter were evaluated. The ground state of Cu2+ is dx2-y2 (2B1g state) and the site symmetry around Cu2+ is tetragonally distorted octahedral. A broad optical absorption band was observed for all the glasses containing Cu2+ ions corresponding to the 2B1g → 2B2g transition. The optical band gap and Urbach energy values are calculated.

  20. Biosorption of Cu2+ and Pb2+ using sophora alopecuroides residue

    Science.gov (United States)

    Feng, N.; Fan, W.; Zhu, M.; Zhang, Y.

    2016-08-01

    Sophora alopecuroides residue (SAP), a kind of traditional Chinese herbal medicine residue, was developed in an alternative biosorbent for the removal Cu2+ and Pb2+ in simulated wastewater. The morphology and surface texture of SAP were characterized by scanning electron microscopy, which showed a loose and porous structure. The biosorption experiments of Cu2+ and Pb2+ onto SAP were investigated by using batch techniques. High biosorption percentage appeared at pH values of 4.5-6.0. The experimental data followed the second-order kinetic model well. Equilibrium fit with the Langmuir isotherm model well. The maximum biosorption capacity of an adsorbent at 25 °C was respectively 60.6 mg/g Cu2+ and 128.1 mg/g Pb2+. The findings of the present study show that SAP is an attractive and effective biosorbent for Cu2+ and Pb2+.

  1. Synthesis of Cu2O from CuO thin films: Optical and electrical properties

    Directory of Open Access Journals (Sweden)

    Dhanya S. Murali

    2015-04-01

    Full Text Available Hole conducting, optically transparent Cu2O thin films on glass substrates have been synthesized by vacuum annealing (5×10−6 mbar at 700 K for 1 hour of magnetron sputtered (at 300 K CuO thin films. The Cu2O thin films are p-type and show enhanced properties: grain size (54.7 nm, optical transmission 72% (at 600 nm and Hall mobility 51 cm2/Vs. The bulk and surface Valence band spectra of Cu2O and CuO thin films are studied by temperature dependent Hall effect and Ultra violet photo electron Spectroscopy (UPS. CuO thin films show a significant band bending downwards (due to higher hole concentration than Cu2O thin films.

  2. Influence of Au Nanoparticle Shape on Au@Cu2O Heterostructures

    Directory of Open Access Journals (Sweden)

    Jie Zhu

    2015-01-01

    Full Text Available Synthesis of metal-semiconductor heterostructures may allow the combination of function of the corresponding components and/or the enhanced performance resulting from the interactions between all the components. In this paper, Au@Cu2O core-shell heterostructures are prepared by a seed-growth method, using different-shaped Au nanocrystals as the seeds such as nanorods, octahedra, decahedra, dots, and nanocubes. The results revealed that the final structure of Au@Cu2O was greatly influenced by the shape of the seeds used. Exposure of Cu2O{111} and Cu2O{001} favored when the overgrowth happened on Au{111} and Au{001} surface, respectively. The size of the product can also be tuned by the amount of the seeds. The results reported here provide a thinking clue to modulate the shape and size of core-shell nanocrystals, which is useful in developing new materials with desired performance.

  3. Study on Characteristics of CdS/Cu2S Photovoltaic Cell

    International Nuclear Information System (INIS)

    Nwe Nwe Htun

    2011-12-01

    In this paper the CdS-Cu2S photovoltaic cell has been prepared and characteristiced by using evaporation method on glass substrate. CdS film was deposited on the Pyrex glass substrate by evaporation and Cu2S layer was obtained by electroplating in a dilute acqueous solution of CusO4 at room temperature. Silver electrode was applied to the electroplated surface. The results of electrical and optical characteristics of the CdS-Cu2S hetrojunction were investigated. The photovoltaic response has been observed under various illuminated intensity for different wavelengths in visible region. It was found to be the photovoltage and photocurrent varying with different light intensities. It can be concluded that formation of a low resistivity CdS film and Cu2S layer play a big role in obtaining a high efficiency cell.

  4. Spontaneous electric polarization in the B-site magnetic spinel GeCu2O4

    Science.gov (United States)

    Yanda, Premakumar; Ghara, Somnath; Sundaresan, A.

    2018-04-01

    We report the observation of a spontaneous electric polarization at the antiferromagnetic ordering temperature (TN ∼ 33 K) of Cu2+ ions in the B-site magnetic spinel GeCu2O4, synthesized at high pressure and high temperature. This compound is known to crystallize in a tetragonal structure (space group I41/amd) due to Jahn-Teller distortion of Cu2+ ions and exhibit a collinear up-up-down-down (↑↑↓↓) antiferromagnetic spin configuration below TN. We found a clear dielectric anomaly at TN, where an electric polarization appears in the absence of applied magnetic field. The electric polarization is suppressed by applied magnetic fields, which demonstrates that the compound GeCu2O4 is a type-II multiferroic.

  5. Ultrathin Cu2O as an efficient inorganic hole transporting material for perovskite solar cells

    KAUST Repository

    Yu, Weili

    2016-02-18

    We demonstrate that ultrathin P-type Cu2O thin films fabricated by a facile thermal oxidation method can serve as a promising hole-transporting material in perovskite solar cells. Following a two-step method, inorganic-organic hybrid perovskite solar cells were fabricated and a power conversion efficiency of 11.0% was achieved. We find that the thickness and properties of Cu2O layers must be precisely tuned in order to achieve the optimal solar cell performance. The good performance of such perovskite solar cells can be attributed to the unique properties of ultrathin Cu2O, including high hole mobility, good energy level alignment with CH3NH3PbI3, and longer lifetime of photo-excited carriers. Combining merits of low cost, facile synthesis, and high device performance, ultrathin Cu2O films fabricated via thermal oxidation hold promise for facilitating the developments of industrial-scale perovskite solar cells.

  6. p-Cu2O-shell/n-TiO2-nanowire-core heterostucture photodiodes

    Directory of Open Access Journals (Sweden)

    Hsueh Ting-Jen

    2011-01-01

    Full Text Available Abstract This study reports the deposition of cuprous oxide [Cu2O] onto titanium dioxide [TiO2] nanowires [NWs] prepared on TiO2/glass templates. The average length and average diameter of these thermally oxidized and evaporated TiO2 NWs are 0.1 to 0.4 μm and 30 to 100 nm, respectively. The deposited Cu2O fills gaps between the TiO2 NWs with good step coverage to form nanoshells surrounding the TiO2 cores. The p-Cu2O/n-TiO2 NW heterostructure exhibits a rectifying behavior with a sharp turn-on at approximately 0.9 V. Furthermore, the fabricated p-Cu2O-shell/n-TiO2-nanowire-core photodiodes exhibit reasonably large photocurrent-to-dark-current contrast ratios and fast responses.

  7. 8 COPPER (I) OXIDE (Cu2O) BASED SOLAR CELLS - A REVIEW

    African Journals Online (AJOL)

    DR. AMINU

    (metal/semiconductor) barrier Cu2O solar cells, where different low work function metals ... The sun has a reasonable stable life time ... practical solution to the global energy problems; ... compounds balance their structures by the presence.

  8. Color superconductivity

    International Nuclear Information System (INIS)

    Wilczek, F.

    1997-01-01

    The asymptotic freedom of QCD suggests that at high density - where one forms a Fermi surface at very high momenta - weak coupling methods apply. These methods suggest that chiral symmetry is restored and that an instability toward color triplet condensation (color superconductivity) sets in. Here I attempt, using variational methods, to estimate these effects more precisely. Highlights include demonstration of a negative pressure in the uniform density chiral broken phase for any non-zero condensation, which we take as evidence for the philosophy of the MIT bag model; and demonstration that the color gap is substantial - several tens of MeV - even at modest densities. Since the superconductivity is in a pseudoscalar channel, parity is spontaneously broken

  9. Color superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Wilczek, F. [Institute for Advanced Study, Princeton, NJ (United States)

    1997-09-22

    The asymptotic freedom of QCD suggests that at high density - where one forms a Fermi surface at very high momenta - weak coupling methods apply. These methods suggest that chiral symmetry is restored and that an instability toward color triplet condensation (color superconductivity) sets in. Here I attempt, using variational methods, to estimate these effects more precisely. Highlights include demonstration of a negative pressure in the uniform density chiral broken phase for any non-zero condensation, which we take as evidence for the philosophy of the MIT bag model; and demonstration that the color gap is substantial - several tens of MeV - even at modest densities. Since the superconductivity is in a pseudoscalar channel, parity is spontaneously broken.

  10. Hydrogenation properties of Mg1-xM1xCu2 (M1=La and Nd) with larger interstitial sites than MgCu2

    International Nuclear Information System (INIS)

    Tsushio, Y.

    1998-01-01

    The hydrogenation properties of C15 compounds are controlled by crystal structure, the size of the interstitial hole being an especially important factor. Its effect on the hydrogenation properties of MgCu 2 substituted with rare earth elements of various radii is discussed and the limit in controlling the crystal structure by conventional substitution is explained. (orig.)

  11. A Au/Cu2O-TiO2 system for photo-catalytic hydrogen production. A pn-junction effect or a simple case of in situ reduction?

    KAUST Repository

    Sinatra, Lutfan

    2015-02-01

    Photo-catalytic H2 production from water has been studied over Au-Cu2O nanoparticle deposited on TiO2 (anatase) in order to probe into both the plasmon resonance effect (Au nanoparticles) and the pn-junction at the Cu2O-TiO2 interface. The Au-Cu2O composite is in the form of ∼10 nm Au nanoparticles grown on ∼475 nm Cu2O octahedral nanocrystals with (111) facets by partial galvanic replacement. X-ray Photoelectron Spectroscopy (XPS) Cu2p and Auger L3M4,5M4,5 lines indicate that the surface of Cu2O is mainly composed of Cu+. The rate for H2 production (from 95 water/5 ethylene glycol; vol.%) over 2 wt.% (Au/Cu2O)-TiO2 is found to be ∼10 times faster than that on 2 wt.% Au-TiO2 alone. Raman spectroscopy before and after reaction showed the disappearance of Cu+ lines (2Eu) at 220 cm-1. These observations coupled with the induction time observed for the reaction rate suggest that in situ reduction from Cu+ to Cu0 occurs upon photo-excitation. The reduction requires the presence of TiO2 (electron transfer). The prolonged activity of the reaction (with no signs of deactivation) despite the reduction to Cu0 indicates that the latter takes part in the reaction by providing additional sites for the reaction, most likely as recombination centers for hydrogen atoms to form molecular hydrogen. This phenomenon provides an additional route for enhancing the efficiency and lifetime of Cu2O-TiO2 photocatalytic systems, beyond the usually ascribed pn-junction effect.

  12. Synthesis, Characterization and Catalytic Activity of Cu/Cu2O Nanoparticles Prepared in Aqueous Medium

    Directory of Open Access Journals (Sweden)

    Sayed M. Badawy

    2015-07-01

    Full Text Available Copper/Copper oxide (Cu/Cu2O nanoparticles were synthesized by modified chemical reduction method in an aqueous medium using hydrazine as reducing agent and copper sulfate pentahydrate as precursor. The Cu/Cu2O nanoparticles were characterized by X-ray Diffraction (XRD, Energy Dispersive X-ray Fluorescence (EDXRF, Scanning Electron Microscope (SEM, and Transmission Electron Microscope (TEM. The analysis revealed the pattern of face-centered cubic (fcc crystal structure of copper Cu metal and cubic cuprites structure for Cu2O. The SEM result showed monodispersed and agglomerated particles with two micron sizes of about 180 nm and 800 nm, respectively. The TEM result showed few single crystal particles of face-centered cubic structures with average particle size about 11-14 nm. The catalytic activity of Cu/Cu2O nanoparticles for the decomposition of hydrogen peroxide was investigated and compared with manganese oxide MnO2. The results showed that the second-order equation provides the best correlation for the catalytic decomposition of H2O2 on Cu/Cu2O. The catalytic activity of hydrogen peroxide by Cu/Cu2O is less than the catalytic activity of MnO2 due to the presence of copper metal Cu with cuprous oxide Cu2O. © 2015 BCREC UNDIP. All rights reservedReceived: 6th January 2015; Revised: 14th March 2015; Accepted: 15th March 2015How to Cite: Badawy, S.M., El-Khashab, R.A., Nayl, A.A. (2015. Synthesis, Characterization and Catalytic Activity of Cu/Cu2O Nanoparticles Prepared in Aqueous Medium. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (2: 169-174. (doi:10.9767/bcrec.10.2.7984.169-174 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.7984.169-174  

  13. Adsorption and desorption of Cu2+ on paddy soil aggregates pretreated with different levels of phosphate.

    Science.gov (United States)

    Dai, Jun; Wang, Wenqin; Wu, Wenchen; Gao, Jianbo; Dong, Changxun

    2017-05-01

    Interactions between anions and cations are important for understanding the behaviors of chemical pollutants and their potential risks in the environment. Here we prepared soil aggregates of a yellow paddy soil from the Taihu Lake region, and investigated the effects of phosphate (P) pretreatment on adsorption-desorption of Cu 2+ of soil aggregates, free iron oxyhydrates-removed soil aggregates, goethite, and kaolinite with batch adsorption method. The results showed that Cu 2+ adsorption was reduced on the aggregates pretreated with low concentrations of P, and promoted with high concentrations of P, showing a V-shaped change. Compared with the untreated aggregates, the adsorption capacity of Cu 2+ was reduced when P application rates were lower than 260, 220, 130 and 110mg/kg for coarse, clay, silt and fine sand fractions, respectively. On the contrary, the adsorption capacity of Cu 2+ was higher on P-pretreated soil aggregates than on the control ones when P application rates were greater than those values. However, the desorption of Cu 2+ was enhanced at low levels of P, but suppressed at high levels of P, displaying an inverted V-shaped change over P adsorption. The Cu 2+ adsorption by the aggregate particles with and without P pretreatments was well described by the Freundlich equation. Similar results were obtained on P-pretreated goethite. However, such P effects on Cu 2+ adsorption-desorption were not observed on kaolinite and free iron oxyhydrates-removed soil aggregates. The present results indicate that goethite is one of the main soil substances responsible for the P-induced promotion and inhibition of Cu 2+ adsorption. Copyright © 2016. Published by Elsevier B.V.

  14. Comparative Compton scattering studies in Cu2O and Ag2O

    International Nuclear Information System (INIS)

    Bandyopadhyay, S.; Chatterjee, A.K.; Saha, S.K.; Chatterjee, A.

    1994-01-01

    Compton scattering studies in polycrystalline Cu 2 O and Ag 2 O with 59.54 keV γ radiation are reported. A comparison has been made between the valance Compton profiles of these two components scaled to lattice momentum by normalizing them to equal electron density for outer valence electrons, and this comparison shows some differences between the bonding characters of Cu 2 O and Ag 2 O. (author)

  15. New electrochemiluminescence catalyst: Cu2O semiconductor crystal and the enhanced activity of octahedra synthesized by iodide ions coordination

    DEFF Research Database (Denmark)

    Zhang, Ling; Qi, Liming; Gao, Wenyue

    2017-01-01

    Cuprous oxide (Cu2O) crystals are usually used as the photocatalysts of water splittings and carbon monoxide oxidations. Herein, we report the new catalytic properties of Cu2O to the electrochemilumenescence (ECL) reactions of luminol and oxygen. Adjusting the shape of Cu2O microcrystals from cub...

  16. Superconducting magnet

    Science.gov (United States)

    1985-01-01

    Extensive computer based engineering design effort resulted in optimization of a superconducting magnet design with an average bulk current density of approximately 12KA/cm(2). Twisted, stranded 0.0045 inch diameter NbTi superconductor in a copper matrix was selected. Winding the coil from this bundle facilitated uniform winding of the small diameter wire. Test coils were wound using a first lot of the wire. The actual packing density was measured from these. Interwinding voltage break down tests on the test coils indicated the need for adjustment of the wire insulation on the lot of wire subsequently ordered for construction of the delivered superconducting magnet. Using the actual packing densities from the test coils, a final magnet design, with the required enhancement and field profile, was generated. All mechanical and thermal design parameters were then also fixed. The superconducting magnet was then fabricated and tested. The first test was made with the magnet immersed in liquid helium at 4.2K. The second test was conducted at 2K in vacuum. In the latter test, the magnet was conduction cooled from the mounting flange end.

  17. Electricity generation from banana peels in an alkaline fuel cell with a Cu2O-Cu modified activated carbon cathode.

    Science.gov (United States)

    Liu, Peng; Liu, Xianhua; Dong, Feng; Lin, Qingxia; Tong, Yindong; Li, Yang; Zhang, Pingping

    2018-08-01

    Low-cost and highly active catalyst for oxygen reduction reaction is of great importance in the design of alkaline fuel cells. In this work, Cu 2 O-Cu composite catalyst has been fabricated by a facile laser-irradiation method. The addition of Cu 2 O-Cu composite in activated carbon air-cathode greatly improves the performance of the cathode. Our results indicate the enhanced performance is likely attributed to the synergistic effect of high conductivity of Cu and the catalytic activity of Cu 2 O towards the oxygen reduction reaction. Furthermore, an alkaline fuel cell equipped with the composite air-cathode has been built to turn banana peels into electricity. Peak power density of 16.12Wm -2 is obtained under the condition of 3M KOH and 22.04gL -1 reducing sugar, which is higher than other reported low-temperature direct biomass alkaline fuel cells. HPLC results indicate the main oxidation products in the alkaline fuel cell were small organic acids. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. Melt formed superconducting joint between superconducting tapes

    International Nuclear Information System (INIS)

    Benz, M.G.; Knudsen, B.A.; Rumaner, L.E.; Zaabala, R.J.

    1992-01-01

    This patent describes a superconducting joint between contiguous superconducting tapes having an inner laminate comprised of a parent-metal layer selected from the group niobium, tantalum, technetium, and vanadium, a superconductive intermetallic compound layer on the parent-metal layer, a reactive-metal layer that is capable of combining with the parent-metal and forming the superconductive intermetallic compound, the joint comprising: a continuous precipitate of the superconductive intermetallic compound fused to the tapes forming a continuous superconducting path between the tapes

  19. Dielectric properties investigation of Cu2O/ZnO heterojunction thin films by electrodeposition

    International Nuclear Information System (INIS)

    Li, Qiang; Xu, Mengmeng; Fan, Huiqing; Wang, Hairong; Peng, Biaolin; Long, Changbai; Zhai, Yuchun

    2013-01-01

    Highlights: ► Bottom-up self-assembly Cu 2 O/ZnO heterojunction was fabricated by electrochemical deposition on indium tin oxide (ITO) flexible substrate (polyethylene terephthalate-PET). ► The dielectric response of Cu 2 O/ZnO heterojunction thin films had been investigated. ► The universal dielectric response was used to investigate the hopping behavior in Cu 2 O/ZnO heterojunction. -- Abstract: Structures and morphologies of the Cu 2 O/ZnO heterojunction electrodeposited on indium tin oxide (ITO) flexible substrate (polyethylene terephthalate-PET) were investigated by X-ray diffraction (XRD), scanning electronic microscopy (SEM), high resolution transmission electron microscopy (HRTEM), respectively. The dielectric response of bottom-up self-assembly Cu 2 O/ZnO heterojunction was investigated. The low frequency dielectric dispersion (LFDD) was observed. The universal dielectric response (UDR) was used to investigate the frequency dependence of dielectric response for Cu 2 O/ZnO heterojunction, which was attributed to the long range and the short range hopping charge carriers at the low frequency and the high frequency region, respectively

  20. Cu and Cu2O films with semi-spherical particles grown by electrochemical deposition

    International Nuclear Information System (INIS)

    Zheng, Jin You; Jadhav, Abhijit P.; Song, Guang; Kim, Chang Woo; Kang, Young Soo

    2012-01-01

    Cu and Cu 2 O films can be prepared on indium-doped tin oxide glass substrates by simple electrodeposition in a solution containing 0.1 M Cu(NO 3 ) 2 and 3 M lactic acid at different pH values. At low pH (pH = 1.2), the uniform Cu films were obtained; when pH ≥ 7, the pure Cu 2 O films can be deposited. Especially, at pH = 11, the deposited Cu 2 O films exhibited cubic surface morphology exposing mainly {100} plane; in contrast, the films consisting of semi-spherical particles were obtained when the solution was being stirred for 2 weeks prior to use. The possible growth process and mechanism were comparatively discussed. - Highlights: ► Cu and Cu 2 O films were prepared by facile electrodeposition. ► Electrodeposition was preformed in electrolyte at different pH values. ► Dendritic Cu films were obtained at 1.2 pH with relatively high deposition potential. ► Semi-spherical Cu 2 O films were obtained with solution at 11 pH and stirred for 2 weeks. ► The possible growth mechanism of semi-spherical Cu 2 O films was discussed.

  1. Preparation and properties of KCl-doped Cu2O thin film by electrodeposition

    International Nuclear Information System (INIS)

    Yu, Xiaojiao; Li, Xinming; Zheng, Gang; Wei, Yuchen; Zhang, Ama; Yao, Binghua

    2013-01-01

    With the indium tin oxide-coated glass as working electrode, cuprous oxide thin film is fabricated by means of electrodeposition. The effects of KCl doped and annealing treatment upon Cu 2 O thin film morphology, surface resistivity, open-circuit voltage, electric conduction types and visible light response are studied. The research results indicate that KCl doped has a great effect upon Cu 2 O crystal morphology, thus, making Cu 2 O thin film surface resistivity drop, and the open-circuit voltage increase and that electric conduction types are transformed from p type into n type, and the visible light (400–500 nm) absorption rate is slightly reduced. Annealing treatment can obviously decrease Cu 2 O thin film surface resistivity and improve its open-circuit voltage. When KCl concentration in electrolytic solution reaches 7 mmol/L, Cu 2 O thin film morphology can be changed from the dendritic crystal into the cubic crystal and Cu 2 O thin film surface resistivity decreases from the initial 2.5 × 10 6 Ω cm to 8.5 × 10 4 Ω cm. After annealing treatment at 320 °C for 30 min, the surface resistivity decreases to 8.5 × 10 2 Ω cm, and the open-circuit voltage increases from the initial 3.1 mV to 79.2 mV.

  2. A new rhodamine B based fluorometric chemodosimeter for Cu2+ ion in aqueous and cellular media

    International Nuclear Information System (INIS)

    Kempahanumakkagaari, Suresh Kumar; Thippeswamy, Ramakrishnappa; Malingappa, Pandurangappa

    2014-01-01

    A simple, sensitive and selective fluorescent chemo dosimeter rhodamine B phenyl hydrazide (RBPH) for Cu 2+ was proposed. This probe is non fluorescent and colorless but exhibits fluorescent enhancement at 580 nm and displayed color change from colorless to pink for Cu 2+ in the pH range 1–6. Fluorescence microscope experimental results reveals that this chemo sensor is cell permeable and can be used for fluorescence imaging of Cu 2+ ions in living cells. This probe can detect Cu 2+ with good linear relationships from 10 to 100 nM with r=0.99971 then limit of detection was found to be 0.015 nM with ±0.91% RSD at 10 nM concentrations. -- Highlights: • The new sensitive, highly selective fluorescent chemodosimeter for Cu 2+ based on spirolactam ring opening process has been proposed. • The probe posse’s excellent cell permeability and it has been applied for fluorescence imaging of Cu 2+ ions in MCF-7 cell lines. • The protocol has been successfully applied for copper determination in blood and urine samples

  3. Highly selective detection of glutathione using a NIP/Cu2+ complex fluorescent probe

    International Nuclear Information System (INIS)

    Liang Wenrui; Zhao Zhi; Zhang Yang; Wang Qiusheng; Zhao Xin; Ouyang Jie

    2012-01-01

    A novel fluorescent compound, 4-(trimethyl ammonium chloride)acetamide-2-(1H-naphtho[2,3-d]imidazol-2-yl)phenol (TMACA-NIP), was synthesized and used as a fluorescent probe for detecting glutathione reduced (GSH). The new NIP-based probe exhibited high fluorescence in water, which was quenched during the presence of copper (II) due to the complexation between TMACA-NIP and Cu 2+ . But after adding GSH into the TMACA-NIP and Cu 2+ system, the fluorescence of TMACA-NIP was recovered because the binding force between GSH and Cu 2+ is stronger than that between TMACA-NIP and Cu 2+ , which destroys the equilibrium between NIP and copper (II) ions and releases the fluorescence probe of TMACA-NIP. This three-component competing system of NIP/Cu 2+ /GSH can be used to detect GSH simply and rapidly. - Highlights: ► A novel fluorescence probe was developed to detect GSH that operates in aqueous solution. ► TMACA-NIP was synthesized and employed as “read-out” units of NIP/Cu 2+ /GSH. ► NIP-based probe shows high selectivity over other sulfhydryl compounds.

  4. Preparation and characterization of Cu2SnS3 thin films by electrodeposition

    Science.gov (United States)

    Patel, Biren; Narasimman, R.; Pati, Ranjan K.; Mukhopadhyay, Indrajit; Ray, Abhijit

    2018-05-01

    Cu2SnS3 thin films were electrodeposited on F:SnO2/Glass substrates at room temperature by using aqueous solution. Copper and tin were first electrodeposited from single bath and post annealed in the presence of sulphur atmosphere to obtain the Cu2SnS3 phase. The Cu2SnS3 phase with preferred orientation along the (112) crystal direction grows to greater extent by the post annealing of the film. Raman analysis confirms the monoclinic crystal structure of Cu2SnS3 with principle mode of vibration as A1 (symmetric breathing mode) corresponding to the band at 291 cm-1. It also reveals the benign coexistence of orthorhombic Cu3SnS4 and Cu2SnS7 phases. Optical properties of the film show direct band gap of 1.25 eV with a high absorption coefficient of the order of 104 cm-1 in the visible region. Photo activity of the electrodeposited film was established in two electrode photoelectro-chemical cell, where an open circuit voltage of 91.6 mV and a short circuit current density of 10.6 µA/cm2 were recorded. Fabrication of Cu2SnS3 thin film heterojunction solar cell is underway.

  5. Effects of Cu(2+) and Zn(2+) on growth and physiological characteristics of green algae, Cladophora.

    Science.gov (United States)

    Cao, De-ju; Xie, Pan-pan; Deng, Juan-wei; Zhang, Hui-min; Ma, Ru-xiao; Liu, Cheng; Liu, Ren-jing; Liang, Yue-gan; Li, Hao; Shi, Xiao-dong

    2015-11-01

    Effects of various concentrations of Cu(2+) and Zn(2+) (0.0, 0.1, 0.25, 0.5, or 1.0 mg/L) on the growth, malondialdehyde (MDA), the intracellular calcium, and physiological characteristics of green algae, Cladophora, were investigated. Low Zn(2+) concentrations accelerated the growth of Cladophora, whereas Zn(2+) concentration increases to 0.25 mg/L inhibited its growth. Cu(2+) greatly influences Cladophora growth. The photosynthesis of Cladophora decreased under Zn(2+) and Cu(2+) stress. Cu(2+) and Zn(2+) treatment affected the content of total soluble sugar in Cladophora and has small increases in its protein content. Zn(2+) induced the intracellular calcium release, and copper induced the intracellular calcium increases in Cladophora. Exposure to Cu(2+) and Zn(2+) induces MDA in Cladophora. The stress concent of Cu(2+) was strictly correlated with the total soluble sugar content, Chla+Chlb, and MDA in Cladophora, and the stress concent of Zn(2+) was strictly correlated with the relative growth rate (RGR) and MDA of Cladophora.

  6. Characterisation of the antiferromagnetic transition of Cu2FeSnS4, the synthetic analogue of stannite

    Science.gov (United States)

    Caneschi, A.; Cipriani, C.; di Benedetto, F.; Sessoli, R.

    2003-04-01

    Magnetisation measurements between 260 and 1.9K were performed on the synthetic analogue of stannite, Cu_2FeSnS_4, tetragonal Ioverline{4}2m. Fe(II) ions, in the high spin S=2 configuration for tetrahedral coordination, are responsible for the high temperature paramagnetism. In agreement with Bernardini et al. (2000), an antiferromagnetic transition was observed, lowering temperature below 8K. Refined measurements evidenced a T_N=6.1K for the Néel temperature. In spite of a small difference, observed in the behaviour between the zero-field cooled and the field cooled curves, which suggests the possible presence of a spin-glass phase, the AC measurements did not provide evidence of dependence of the magnetic susceptibility on frequency, as expected in spin-glass systems. On the basis of the experimental data, in agreement with the existent literature (Fries et al., 1997), a collinear antiferromagnetic structure should be preferred. The Fe ions, in fact, are distributed in two sublattices obtained by magnetic differentiation of the symmetry equivalent (0,0,0) and (frac{1}{2}frac{1}{2}frac{1}{2}) Fe positions (wyckoff: 2a). The low value for the Nèel temperature, as compared e.g. to the room-temperature antiferromagnet chalcopyrite (CuFeS_2), very close in composition and structure to stannite, is to be related to the increased distance between the Fe ions (˜6.6Å). This weak interaction is not detected in natural samples, where diamagnetic Zn(II) replace paramagnetic Fe(II), thus increasing the mean Fe-Fe distance. Fries, T., Shapira, Y., Palacio, F., Moròn, M.C., McIntyre, G.J., Kershaw, R., Wold, A. and McNiff, E.J. Jr. (1997): Mangetic ordering of the antiferromagnet Cu_2MnSnS_4 from magnetisation and neutron-scattering measurements. Phys. Rev. B, 6(9), 5424-5431 Bernardini, G.P., Borrini, D., Caneschi, A. Di Benedetto, F., Gatteschi, D., Ristori, S. and Romanelli, M. (2000): EPR and SQUID magnetometry study of Cu_2FeSnS_4 (stannite) and Cu_2ZnSnS_4 (kesterite

  7. Sample-length dependence of the critical current of slightly and significantly bent-damaged Bi2223 superconducting composite tape

    International Nuclear Information System (INIS)

    Ochiai, S; Fujimoto, M; Okuda, H; Oh, S S; Ha, D W

    2007-01-01

    The local critical current along a sample length is different from position to position in a long sample, especially when the sample is damaged by externally applied strain. In the present work, we attempted to reveal the relation of the distribution of the local critical current to overall critical current and the sample-length dependence of critical current for slightly and significantly damaged Bi2223 composite tape samples. In the experiment, 48 cm long Bi2223 composite tape samples, composed of 48 local elements with a length of 1 cm and 8 parts with a length 6 cm, were bent by 0.37 and 1.0% to cause slight and significant damage, respectively. The V-I curve, critical current (1 μV cm -1 criterion) and n value were measured for the overall sample as well as for the local elements and parts. It was found that the critical current distributions of the 1 cm elements at 0.37 and 1.0% bending strains are described by the three-parameter- and bimodal Weibull distribution functions, respectively. The critical current of a long sample at both bending strains could be described well by substituting the distributed critical current and n value of the short elements into the series circuit model for voltage generation. Also the measured relation of average critical current to sample length could be reproduced well in the computer by a Monte Carlo simulation method. It was shown that the critical current and n value decrease with increasing sample length at both bending strains. The extent of the decrease in critical current with sample length is dependent on the criterion of the critical current; the critical current decreases only slightly under the 1 μV cm -1 criterion which is not damage-sensitive, while it decreases greatly with increasing sample length under damage-sensitive criteria such as the 1 μV one

  8. Reactive pulsed laser deposition of Cu2ZnSnS4 thin films in H2S

    International Nuclear Information System (INIS)

    Surgina, G.D.; Zenkevich, A.V.; Sipaylo, I.P.; Nevolin, V.N.; Drube, W.; Teterin, P.E.; Minnekaev, M.N.

    2013-01-01

    Cu 2 ZnSnS 4 (CZTS) thin films have been grown by reactive pulsed laser deposition in H 2 S atmosphere, combining the alternate ablation from the metallic (Cu) and alloyed (Zn x Sn) targets at room temperature. The morphological, structural and optical properties of as grown CZTS thin films with varying compositions as well as upon annealing in N 2 atmosphere are investigated by Rutherford backscattering spectrometry, X-ray diffraction, Raman spectroscopy and optical spectrophotometry. The chemical bonding in the “bulk” of the CZTS films is elucidated via hard X-ray photoemission spectroscopy measurements. The formation of the good quality stoichiometric polycrystalline CZTS films is demonstrated upon optimization of the growth parameters. - Highlights: ► The new method of Cu 2 ZnSnS 4 (CZTS) thin films growth in H 2 S was realized. ► CZTS films were grown by pulsed laser deposition from Cu and alloyed Zn–Sn targets. ► The effect of the processing parameters on the CZTS properties was investigated. ► The chemical bonding in the “bulk” of CZTS films was studied

  9. Superconducting ac cable

    Science.gov (United States)

    Schmidt, F.

    1980-11-01

    The components of a superconducting 110 kV ac cable for power ratings or = 2000 MVA were developed. The cable design is of the semiflexible type, with a rigid cryogenic envelope containing a flexible hollow coaxial cable core. The cable core consists of spirally wound Nb-A1 composite wires electrically insulated by high pressure polyethylene tape wrappings. A 35 m long single phase test cable with full load terminals rated at 110 kV and 10 kA was constructed and successfully tested. The results obtained prove the technical feasibility and capability of this cable design.

  10. Superconducting ac cable

    International Nuclear Information System (INIS)

    Schmidt, F.

    1980-01-01

    The components of a superconducting 110 kV ac cable for power ratings >= 2000 MVA have been developed. The cable design especially considered was of the semiflexible type, with a rigid cryogenic envelope and flexible hollow coaxial cable cores pulled into the former. The cable core consists of spirally wound Nb-Al composite wires and a HDPE-tape wrapped electrical insulation. A 35 m long single phase test cable with full load terminations for 110 kV and 10 kA was constructed and successfully tested. The results obtained prove the technical feasibility and capability of our cable design. (orig.) [de

  11. Influence of Precursor Composition on the Microstructure and Superconducting Properties of Dy-Ba-Cu-O filaments

    International Nuclear Information System (INIS)

    Ikebe, Y; Ban, E; Matsuoka, Y; Nishijima, G; Watanabe, K

    2006-01-01

    Dy-Ba-Cu-O filaments have been successfully fabricated by a solution spinning method. The relationship between the partial melting temperature and the transport J c value at 77 K of the filamentary sample was systematically investigated. Two kinds of precursor filaments with starting composition of Dy:Ba:Cu = 1.18:2.12:3.09 (sample A)and Dy:Ba:Cu = 1.00:2.00:3.00 (sample B) were partially melted in 1%O 2 + Ar atmospheric gas and oxygenated in pure 100% O 2 gas. Samples partially melted at a wide temperature range of 990-1040 deg. C had J c values higher than 10 4 A/cm 2 . Both sample A and sample B partially melted at 1020 deg. C exhibited the maximum J c value higher than 4.2 x 10 4 A/cm 2 and 2.0 x 10 4 A/cm 2 , respectively. These samples had a dense microstructure consisting predominantly of Dy123 and finely dispersed Dy211 particles. The Dy211 particles with a diameter of about 1μm were finely dispersed in sample A, while the particles with a diameter of about 5μm were observed in sample B. The J c values of both samples were maintained about 2.0 x 10 3 A/cm 2 up to 14 T

  12. Compounds Containing Tetragonal Cu2+ Complexes: Is the dx2–y2–d3z2–r2 Gap a Direct Reflection of the Distortion?

    DEFF Research Database (Denmark)

    García-Fernández, Pablo; Barriuso, María Teresa; García Lastra, Juan Maria

    2013-01-01

    – complex. This internal field, especially important for layered compounds, is shown to explain all puzzling experimental facts on the d–d transitions of the studied systems and is of interest in the search of new Cu2+ and Ag2+ superconducting materials where a strong correlation between Δ...... to be not correct through the study of pure K2CuF4-, KCuF3-, and Cu2+-doped KZnF3 and K2ZnF4 model compounds. Indeed, ab initio calculations prove that Δ in these insulating materials also depends on the internal electric field created by the rest of lattice ions on active electrons confined in a given CuF64...

  13. Superconducting plasmas

    International Nuclear Information System (INIS)

    Ohnuma, Toshiro; Ohno, J.

    1994-01-01

    Superconducting (SC) plasmas are proposed and investigated. The SC plasmas are not yet familiar and have not yet been studied. However, the existence and the importance of SC plasmas are stressed in this report. The existence of SC plasmas are found as follows. There is a fundamental property of Meissner effect in superconductors, which shows a repulsive effect of magnetic fields. Even in that case, in a microscopic view, there is a region of magnetic penetration. The penetration length λ is well-known as London's penetration depth, which is expressed as δ = (m s /μ 0 n s q s 2 ) 1/2 where m s , n s , q s and μ o show the mass, the density, the charge of SC electron and the permeability in free space, respectively. Because this expression is very simple, no one had tried it into more simple and meaningful form. Recently, one of the authors (T.O.) has found that the length can be expressed into more simple and understandable fundamental form as λ = c/ω ps where c = (ε 0 μ 0 ) -1/2 and ω ps = (n s q s 2 /m s ε 0 ) 1/2 are the light velocity and the superconducting plasma frequency. From this simple expression, the penetration depth of the magnetic field to SC is found as a SC plasma skin depth, that is, the fundamental property of SC can be expressed by the SC plasmas. This discovery indicates an importance of the studies of superconducting plasmas. From these points, several properties (propagating modes et al) of SC plasmas, which consist of SC electrons, normal electrons and lattice ions, are investigated in this report. Observations of SC plasma frequency is also reported with a use of Terahertz electromagnet-optical waves

  14. Dansyl-anthracene dyads for ratiometric fluorescence recognition of Cu2+.

    Science.gov (United States)

    Kaur, Kuljit; Kumar, Subodh

    2011-03-21

    Dansyl-anthracene dyads 1 and 2 in CH(3)CN-H(2)O (7:3) selectively recognize Cu(2+) ions amongst alkali, alkaline earth and other heavy metal ions using both absorbance and fluorescence spectroscopy. In absorbance, the addition of Cu(2+) to the solution of dyads 1 or 2 results in appearance of broad absorption band from 200 nm to 725 nm for dyad 1 and from 200 nm to 520 nm for dyad 2. This is associated with color change from colorless to blue (for 1) and fluorescent green (for 2). This bathochromic shift of the spectrum could be assigned to internal charge transfer from sulfonamide nitrogen to anthracene moiety. In fluorescence, under similar conditions dyads 1 and 2 on addition of Cu(2+) selectively quench fluorescence due to dansyl moiety between 520-570 nm (for 1)/555-650 nm (for 2) with simultaneous fluorescence enhancement at 470 nm and 505 nm for dyads 1 and 2, respectively. Hence these dyads provide opportunity for ratiometric analysis of 1-50 μM Cu(2+). The other metal ions viz. Fe(3+), Co(2+), Ni(2+), Cd(2+), Zn(2+), Hg(2+), Ag(+), Pb(2+), Li(+), Na(+), K(+), Mg(2+), Ca(2+), Ba(2+) do not interfere in the estimation of Cu(2+) except Cr(3+) in case of dyad 1. The coordination of dimethylamino group of dansyl unit with Cu(2+) causes quenching of fluorescence due to dansyl moiety between 520-600 nm and also restricts the photoinduced electron transfer from dimethylamino to anthracene moiety to release fluorescence between 450-510 nm. This simultaneous quenching and release of fluorescence respectively due to dansyl and anthracene moieties emulates into Cu(2+) induced ratiometric change.

  15. Physical properties and characterization of RuSr2GdCu2O8 (Ru-1212) grown by top seeded melt textured technique

    International Nuclear Information System (INIS)

    Uthayakumar, S.; Santhosh, P.; Gombos, M.; Babu, M. Ramesh; Jayavel, R.; Vecchione, A.; Pace, S.

    2009-01-01

    Efforts have been made in optimizing growth conditions for bulk textured growth of RuSr 2 GdCu 2 O 8 (Ru-1212) employing top seeded growth technique (TSG). Thermal stability and peritectic temperature (T p ) have been determined by TG-DTA analysis. The study facilitates appropriate thermal treatments to yield good quality sample. The structural study of the as grown sample has been carried out by X-ray diffraction technique. Morphological study by polarized optical microscope (PLOM) and scanning electron microscope (SEM) reveals the growth mechanism. Subsequently, the stoichiometry has been confirmed by energy dispersive X-ray analysis (EDAX). The observed characterization results show the influence of superconducting property on growth technique and allow one to correlate between the physical properties and experimental technique.

  16. Spatially resolved vacuum tunneling spectroscopy on Bi 2Sr 2CaCu 2O 8 by STM at 4.8K

    Science.gov (United States)

    Renner, Ch.; Fischer, Ø.; Kent, A. D.; Mitzi, D. B.; Kapitulnik, A.

    1994-02-01

    We report scanning tunneling spectroscopy investigations on in-situ cleaved superconducting Bi 2Sr 2CaCu 2O 8 single crystals. Although many investigators report reproducible tunneling studies on high temperature superconductors, there nevertheless remains uncertainties about the correct intrinsic shape of the tunneling spectra. We have been able to obtain higly reproducible spectra while scanning single crystal surfaces in many different areas and taking a spectra every 5Å along lines of several hundred Ångstroms. Furthermore, we show that the spectra are independent of modifacations of the barrier obtained by changing the tip/sample distance. The experimental density of states clearly shows some filling of the gap which does not fit with a BCS-like s-wave prediction, even if some scattering in the tunneling process is accounted for.

  17. Spatially resolved vacuum tunneling spectroscopy on Bi2Sr2CaCu2O8 by STM at 4.8K

    International Nuclear Information System (INIS)

    Renner, C.; Fischer, Oe.; Kent, A.D.; Mitzi, D.B.; Kapitulnik, A.

    1994-01-01

    We report scanning tunneling spectroscopy investigations on in-situ cleaved superconducting Bi 2 Sr 2 CaCu 2 O 8 single crystals. Although many investigators report reproducible tunneling studies on high temperature superconductors, there nevertheless remains uncertainties about the correct intrinsic shape of the tunneling spectra. We have been able to obtain highly reproducible spectra while scanning single crystal surfaces in many different areas and taking a spectra every 5A along lines of several hundred AAngstroms. Furthermore, we show that the spectra are independent of modifications of the barrier obtained by changing the tip/sample distance. The experimental density of states clearly shows some filling of the gap which does not fit with a BCS-like s-wave prediction, even if some scattering in the tunneling process is accounted for. (orig.)

  18. Growth of high quality Bi2Sr2CaCu2Oy single crystals by the modified vertical Bridgman method

    International Nuclear Information System (INIS)

    Nagashima, O.; Tanaka, H.; Echizen, Y.; Kishida, S.

    2004-01-01

    We grew Bi 2 Sr 2 CaCu 2 O y (Bi-2212) single crystals by the modified vertical Bridgman (VB) method, and investigated their characteristics in order to clarify the optimum growth conditions for obtaining high-quality Bi-2212 single crystals. The Bi-2212 single crystals were grown changing pulling rates or using starting materials after pre-treatments. We found that the superconducting critical temperature (T c ) of the single crystal prepared at a slow growth rate of 0.25 mm/h was about 88 K and that the single crystals were a Bi-2212 single phase. Moreover, the single crystals grown using the starting materials pre-treated in Ar and O 2 atmospheres, had the T c of about 88 and 86 K, respectively. In addition, both of single crystals were Bi-2212 single phase

  19. Fabrication and characterization of Bi2Sr2CaCu2O8+δ stacks by self-planarizing process

    International Nuclear Information System (INIS)

    Okanoue, K.; Ishida, H.; Funabiki, H.; Hamasaki, K.; Shimakage, N.; Kawakami, A.; Wang, Z.; Abe, H.

    2005-01-01

    We developed a new fabrication process of stacked intrinsic Josephson junctions using superconducting Bi 2 Sr 2 CaCu 2 O 8+δ (Bi-2212) single crystals. In the proposed self-planarizing process, the Bi-2212 crystal around the junction window was modified to insulator by soaking into the solution of dilute (0.05-0.2%) hydrochloric acid for 5 s. Energy dispersive X-ray (EDX) spectroscopy revealed that the acid-treated Bi-2212 exhibited the decrease of Cu and Sr contents in the crystals. The current-voltage characteristic of the stacks showed distinct resistive branches with large hysteresis at 77 K. The number of intrinsic junctions in the stacks linearly decreased with decreasing the concentration of the solution. The well controllability of the number of junctions in the self-planarized stacks may be useful for electronic device applications

  20. The single-crystal multinary compound Cu2ZnSnS4 as an environmentally friendly high-performance thermoelectric material

    Science.gov (United States)

    Nagaoka, Akira; Masuda, Taizo; Yasui, Shintaro; Taniyama, Tomoyasu; Nose, Yoshitaro

    2018-05-01

    We investigated the thermoelectric properties of high-quality p-type Cu2ZnSnS4 single crystals. This material showed two advantages: low thermal conductivity because of lattice scattering caused by the easily formed Cu/Zn disordered structure, and high conductivity because of high doping from changes to the composition. All samples showed a thermal conductivity of 3.0 W m‑1 K‑1 at 300 K, and the Cu-poor sample showed a conductivity of 7.5 S/cm at 300 K because of the high density of shallow-acceptor Cu vacancies. The figure of merit of the Cu-poor Cu2ZnSnS4 reached 0.2 at 400 K, which is 1.4–45 times higher than those of related compounds.

  1. Glass formation and the third harmonic generation of Cu2Se–GeSe2–As2Se3 glasses

    International Nuclear Information System (INIS)

    Reshak, A. H.; Klymovych, O. S.; Zmiy, O. F.; Myronchuk, G. L.; Zamuruyeva, O. V.; Alahmed, Z. A.; Chyský, J.; Bila, Jiri; Kamarudin, H.

    2014-01-01

    We have performed the investigation of the nonlinear optical properties namely the third harmonic generation (THG) of the glass-formation region in the Cu 2 Se–GeSe 2 –As 2 Se 3 system. The samples were synthesized by direct single-temperature method from high-purity elementary substances. We have found that the value of disorder parameter Δ depends on the composition of the glassy alloys. The measurements show that increasing the Cu 2 Se concentration leads to increased slope of the absorption edge, which may be explained by the decrease of the height of random potential relief for the electrons in the tails of the state density which border the band edges. A very sharp increase in the THG at low temperature was observed. Significant enhancement in THG was obtained with decreasing the energy gap, which agreed well with the nonlinear optical susceptibilities obtained from other glasses.

  2. Preparation of Cu2O modified TiO2 nanopowder and its application to the visible light photoelectrocatalytic reduction of CO2 to CH3OH

    Science.gov (United States)

    Li, Bin; Niu, Wenchao; Cheng, Yongwei; Gu, Junjie; Ning, Ping; Guan, Qingqing

    2018-05-01

    Cu2O/TiO2 nanopowders were prepared and used as thin film electrode raw materials for CO2 photoelectroreduction. Characterization results from XRD, TEM, UV-Vis and BET show that Cu2O/TiO2 composites have regular morphology, narrow band gap, excellent textural properties, and exhibits marked response of visible light. The photoelectrocatalytic results show that CO2 can be reduced to formaldehyde (i.e., intermediate) and finally methanol (i.e., end product). In addition, the CO2 photoelectroreduction pathway and the mechanism of photoelectrocatalysis are discussed. In summary, the work reports a potential method of CO2 reduction by visible-light photocatalysis without an external bias.

  3. The state of superconductivity

    International Nuclear Information System (INIS)

    Clark, T.D.

    1981-01-01

    The present status of applications based on the phenomena of superconductivity are reviewed. Superconducting materials, large scale applications, the Josephson effect and its applications, and superconductivity in instrumentation, are considered. The influence that superconductivity has had on modern theories of elementary particles, such as gauge symmetry breaking, is discussed. (U.K.)

  4. Loading of Two Related Metal-Organic Frameworks (MOFs, [Cu2(bdc2(dabco] and [Cu2(ndc2(dabco], with Ferrocene

    Directory of Open Access Journals (Sweden)

    Wolfgang Wenzel

    2011-09-01

    Full Text Available We have studied the loading of two related, similar porous metal-organic frameworks (MOFs [Cu2(bdc2(dabco] (1, and [Cu2(ndc2(dabco] (2 with ferrocene by exposing bulk powder samples to the corresponding vapor. On the basis of powder X-ray diffraction data and molecular dynamics (MD calculations we propose that each pore can store one ferrocene molecule. Despite the rather pronounced similarity of the two MOFs a quite different behavior is observed, for 1 loading with ferrocene leads to an anisotropic 1% contraction, whereas for 2 no deformation is observed. Mössbauer spectroscopy studies reveal that the Fe oxidation level remains unchanged during the process. Time dependent studies reveal that the diffusion constant governing the loading from the gas-phase for 1 is approximately three times larger than the value for 2.

  5. Effect of Cu2+ substitution on the structural, magnetic and electrical properties of gadolinium orthoferrite

    Science.gov (United States)

    Sai Vandana, C.; Hemalatha Rudramadevi, B.

    2018-04-01

    The pure and copper (Cu) substituted Gadolinium orthoferrites, GdFeO3, GdCu0.1Fe0.9O3, GdCu0.2Fe0.8O3 and GdCu0.3Fe0.7O3 were synthesized by conventional solid state method. The structural, morphological, dielectric, magnetic and impedance properties of Cu substituted Gadolinium orthoferrites have been investigated. The crystallographic phase as well as the substitution of Cu2+ ions in the lattice of GdFeO3 is confirmed from the x-ray diffraction patterns. The Fourier transform infrared spectra exhibit two prominent fundamental absorption peaks at ∼417 cm‑1 and 545 cm‑1. These bands are related to inherent stretching vibrations of metals at octahedral and tetrahedral sites respectively. The coercivity (Hc) and saturation magnetization (Ms) of the synthesized samples at different temperatures were determined from the hysteresis plots. Higher coercive values, 598 Oe and 600 Oe were achieved in GdCu0.1Fe0.9O3 ferrites compared to 527 Oe and 360 Oe in pure GdFeO3 at room temperature (300 K) and low temperature (20 k) respectively. Dielectric dispersion has been observed for gadolinium ferrite samples with Maxwell–Wagner type interfacial polarization. The decrease of dielectric constant and dielectric loss tangent with an increase in frequency was observed. The conduction due to charge hopping between localized states was confirmed from AC conductivity measurements. The composition dependent cationic distributions estimated from XRD, magnetic and electrical studies are in good agreement with each other. The achieved results indicate that the substitution of Cu in gadolinium orthoferrite strongly influences the crystal structure, magnetic and electrical properties thereby making them suitable as multiple state memory devices, transducers, electronic field controlled ferromagnetic resonance devices and spintronic devices.

  6. Efficient removal of methyl orange using Cu2O as a dual function catalyst

    Science.gov (United States)

    Zhang, Fan; Dong, Guohui; Wang, Mian; Zeng, Yubin; Wang, Chuanyi

    2018-06-01

    In this study, we synthesized Cu2O particles with rough surfaces by a facile solvothermal method as a dual-function material that can degrade contaminants not only under light irradiation but also in dark circumstance. Both the as-prepared Cu2O and commercial Cu2O exhibited excellent performance for the removal of methyl orange under visible light irradiation through a photocatalysis-based strategy. However, the former was found to show remarkable capability under dark circumstances by means of molecular oxygen activation, while the latter performed poor efficiently under the same condition. This significant difference of performances under dark circumstances was related to rich oxygen vacancies existed on the as-prepared Cu2O surfaces that are associated with the single-electron reduction of O2 to generate radO2-, which play a dominant role in the generation of Cu+. In addition, Cu+ was identified to play key roles in the broken of azo bond. Then, the generated intermediates were mineralized by radOH generated through molecular oxygen activation process. This study could not only deep the understanding of the MO removal mechanism by Cu2O but also show a novel direction of amphibious application for photocatalytic materials.

  7. A Cu2+-selective fluorescent chemosensor based on BODIPY with two pyridine ligands and logic gate

    Science.gov (United States)

    Huang, Liuqian; Zhang, Jing; Yu, Xiaoxiu; Ma, Yifan; Huang, Tianjiao; Shen, Xi; Qiu, Huayu; He, Xingxing; Yin, Shouchun

    2015-06-01

    A novel near-infrared fluorescent chemosensor based on BODIPY (Py-1) has been synthesized and characterized. Py-1 displays high selectivity and sensitivity for sensing Cu2+ over other metal ions in acetonitrile. Upon addition of Cu2+ ions, the maximum absorption band of Py-1 in CH3CN displays a red shift from 603 to 608 nm, which results in a visual color change from pink to blue. When Py-1 is excited at 600 nm in the presence of Cu2+, the fluorescent emission intensity of Py-1 at 617 nm is quenched over 86%. Notably, the complex of Py-1-Cu2+ can be restored with the introduction of EDTA or S2-. Consequently, an IMPLICATION logic gate at molecular level operating in fluorescence mode with Cu2+ and S2- as chemical inputs can be constructed. Finally, based on the reversible and reproducible system, a nanoscale sequential memory unit displaying "Writing-Reading-Erasing-Reading" functions can be integrated.

  8. Josephson effectss in bicrystalline Bi2Sr2CaCu2O8+δ thin films

    International Nuclear Information System (INIS)

    Amrein, T.

    1994-08-01

    A pulsed laser deposition process is developed for preparing high quality thin films of Bi 2 Sr 2 CaCu 2 O x on different substrates. Both microstructural and electrical properties of the superconducting films are well characterized, e.g. by SEM, TEM and AFM. The high reproducability of the thin film quality facilitated a detailed study of Josephson effects in bicrystalline grain boundary junctions (GBJs). Thin films are deposited on commercially available (001) SrTiO 3 bicrystalls and patterned by standard photolithography using wet-etching or Ar + -ion milling. The width of the micobridges ranges from 2 to 111 μm. The critical current densities across grain boundaries of thin film bicrystals have been measured as a function of the tilt angle Θ. For Θ=0 to 45 , the ratio of the grain boundary critical current density to the bulk critical current density decreases exponentially with increasing tilt angle. Microstructure investigations show a rough grain boundary of the superconductor (roughness 100 nm-1 μm) which is not determined by the roughness of the substrate grain boundary (1-3 nm) but by the island-plus-layer growth of the twin domains. The electrical properties are well described by the resistively shunted junction (RSJ) model. The I c R n -product reaches values of 2.2 mV at 4.2 K and 60 μV at 77 K. An optimized design for dc SQUIDs (Θ=24 ) is developed relating to the results of single GBJs. The values of the transfer function (∂V/∂Φ) run up to 74 μV/Φ o . The equivalent flux noise which is measured in a flux-locked loop mode amounts 4.5 to 25 μPhi o Hz in the white noise region for Φ≥25-50 Hz and 13 to 150 μΦ o Hz at 1 Hz. In conclusion, microstructural as well as electrical properties of bicrystalline Bi 2 Sr 2 CaCu 2 O x and YBa 2 Cu 3 O y GBJs are more or less equal. (orig.)

  9. 100 years of superconductivity

    CERN Document Server

    Rogalla, Horst

    2011-01-01

    Even a hundred years after its discovery, superconductivity continues to bring us new surprises, from superconducting magnets used in MRI to quantum detectors in electronics. 100 Years of Superconductivity presents a comprehensive collection of topics on nearly all the subdisciplines of superconductivity. Tracing the historical developments in superconductivity, the book includes contributions from many pioneers who are responsible for important steps forward in the field.The text first discusses interesting stories of the discovery and gradual progress of theory and experimentation. Emphasizi

  10. High-temperature superconductivity

    International Nuclear Information System (INIS)

    Ginzburg, V.L.

    1987-07-01

    After a short account of the history of experimental studies on superconductivity, the microscopic theory of superconductivity, the calculation of the control temperature and its possible maximum value are presented. An explanation of the mechanism of superconductivity in recently discovered superconducting metal oxide ceramics and the perspectives for the realization of new high-temperature superconducting materials are discussed. 56 refs, 2 figs, 3 tabs

  11. Superconducting accelerator technology

    International Nuclear Information System (INIS)

    Grunder, H.A.; Hartline, B.K.

    1986-01-01

    Modern and future accelerators for high energy and nuclear physics rely increasingly on superconducting components to achieve the required magnetic fields and accelerating fields. This paper presents a practical overview of the phenomenon of superconductivity, and describes the design issues and solutions associated with superconducting magnets and superconducting rf acceleration structures. Further development and application of superconducting components promises increased accelerator performance at reduced electric power cost

  12. Experimental study of Pulsed Laser Deposited Cu2ZnSnS 4 (CZTS) thin films for photovoltaic applications

    Science.gov (United States)

    Nandur, Abhishek S.

    Thin film solar cells are gaining momentum as a renewable energy source. Reduced material requirements (15 mum in total thickness) solar cells. Among the various thin film solar absorbers that have been proposed, CZTS (Cu2ZnSnS4) has become the subject of intense interest because of its optimal band gap (1.45 eV), high absorption coefficient (104 cm--1 ) and abundant elemental components. Pulsed Laser Deposition (PLD) provides excellent control over film composition since films are deposited under high vacuum with excellent stoichiometry transfer from the target. Defect-free, near-stoichiometric poly-crystalline CZTS thin films were deposited using PLD from a stoichiometrically close CZTS target (Cu2.6Zn1.1Sn0.7S3.44). The effects of fabrication parameters such as laser energy density, deposition time, substrate temperature and sulfurization (annealing in sulfur) on the surface morphology, composition and optical absorption of the CZTS thin films were examined. The results show that the presence of secondary phases, present both in the bulk and on the surface, affected the electrical and optical properties of the CZTS thin films and the CZTS based TFSCs. After selectively etching away the secondary phases with DIW, HCl and KCN, it was observed that their removal improved the performance of CZTS based TFSCs. Optimal CZTS thin films exhibited an optical band gap of 1.54 eV with an absorption coefficient of 4x10 4cm-1 with a low volume of secondary phases. A TFSC fabricated with the best CZTS thin film obtained from the experimental study done in this thesis showed a conversion efficiency of 6.41% with Voc = 530 mV, Jsc= 27.5 mA/cm2 and a fill factor of 0.44.

  13. Optical anisotropy of Bi2Sr2CaCu2O8

    Science.gov (United States)

    Kim, J. H.; Bozovic, I.; Mitzi, D. B.; Kapitulnik, A.; Harris, J. S., Jr.

    1990-04-01

    The optical anisotropy of Bi2Sr2CaCu2O8 in the 0.08-0.5-eV region is investigated by polarized reflectance measurements on single crystals. A very large anisotropy is found in this spectral region. The in-plane reflectance exhibits metallic behavior, while the c-axis reflectance exhibits insulatorlike behavior. This result is consistent with the large anisotropy found in the resistivity of Bi2Sr2CaCu2O8. Our spectroscopic data suggest that Bi2Sr2CaCu2O8 is a quasi-two-dimensional metal similar to La2-xSrxCuO4.

  14. Fabrication and Optoelectrical Properties of IZO/Cu2O Heterostructure Solar Cells by Thermal Oxidation

    Directory of Open Access Journals (Sweden)

    Cheng-Chiang Chen

    2012-01-01

    Full Text Available Indium zinc oxide (IZO/cupper oxide (Cu2O is a nontoxic nature and an attractive all-oxide candidate for low-cost photovoltaic (PV applications. The present paper reports on the fabrication of IZO/Cu2O heterostructure solar cells which the Cu2O layers were prepared by oxidation of Cu thin films deposited on glass substrate. The measured parameters of cells were the short-circuit current (Isc, the open-circuit voltage (Voc, the maximum output power (Pm, the fill factor (FF, and the efficiency (η, which had values of 0.11 mA, 0.136 V, 5.05 μW, 0.338, and 0.56%, respectively, under AM 1.5 illumination.

  15. Passivation of defects in polycrystalline Cu2O thin films by hydrogen or cyanide treatment

    International Nuclear Information System (INIS)

    Ishizuka, S.; Kato, S.; Okamoto, Y.; Sakurai, T.; Akimoto, K.; Fujiwara, N.; Kobayashi, H.

    2003-01-01

    The effects of the passivation of defects in polycrystalline nitrogen-doped cuprous oxide (Cu 2 O) thin films with hydrogen or cyanide treatment were studied. In the photoluminescence (PL) measurements, although the emission was not observed before treatment, luminescence of Cu 2 O at around 680 nm was observed after each treatment. This improvement in the luminescence property may be due to the passivation of non-radiative recombination centers by H or CN. The hole carrier concentration increased from the order of 10 16 to 10 17 cm -3 with hydrogen or cyanide treatment. From these results, both the hydrogen and cyanide treatments were found to be very effective to passivate defects and improve the optical and electrical properties of polycrystalline Cu 2 O thin films. The thermal stability of the passivation effects by the cyanide treatment is, however, superior to that by the hydrogen treatment

  16. Nanostructured Cu2O thin film electrodes prepared by electrodeposition for rechargeable lithium batteries

    International Nuclear Information System (INIS)

    Bijani, S.; Gabas, M.; Martinez, L.; Ramos-Barrado, J.R.; Morales, J.; Sanchez, L.

    2007-01-01

    Uniform films of Cu 2 O with thickness below 1 μm were prepared from a Cu(II) lactate solution. The deposits were compact and of high purity with the particle size varying from 60 to 400 nm. They were tested as electrodes in lithium batteries and their electrochemical response was consistent with the Cu 2 O + 2e - + 2Li + ↔ 2Cu + Li 2 O reaction. Nevertheless, the reversibility of this reaction was dependent on thickness. Kinetic factors associated with the poor electronic conductivity of Cu 2 O could account for the relevance of the influence of film thickness. The thinnest film, about 300 nm thick, exhibited the best electrochemical performance by sustaining a specific capacity as high as 350 Ah kg -1

  17. A study on metastable superconducting magnets

    International Nuclear Information System (INIS)

    Koyama, Kenichi

    1976-01-01

    It is important to construct superconducting magnets as cheap as possible. One of the methods to achieve such a purpose is to save the superconducting material and operate the magnets at a high current density. Therefore it is useful to investigate the requirements for the operation of metastable superconducting magnets which can work at a current higher than the recovery current. Using the theory of flux jump, we introduce a ''stable current'' below which no flux jump can occur. On a rough approximation, it is given by I sub(s) =√A P sub(i) H sub(e) T sub(o) f(x)/rho where A : cross-section of the composite conductor. P sub(i) : total perimeter of all the superconducting cores. h sub(e) : effective heat transfer coefficient to the liquid helium through the stabilizer. T sub(o) : a characteristic temperature of the superconducting cores. f(x) : a characteristic function for the relative core radius x. rho : effective resistivity of the composite. Then it is shown that superconducting magnets can operate without unexpected normal transitions in the region enclosed by the two curves of I sub(s) and I sub(c). Next, we discuss the characteristics of our saddle shaped superconducting magnet for an one-KW MHD generator. We found that, 1) the magnet does safely operate in the metastable state; 2) the characteristics of the magnet are consistent with our theoretical results. (auth.)

  18. Fluorescence Chemosensory Determination of Cu2+ Using a New Rhodamine–Morpholine Conjugate

    Directory of Open Access Journals (Sweden)

    Zeinab Shekari

    2017-09-01

    Full Text Available A new rhodamine-B carbonyl-morpholine derivative (denoted as RECM was prepared by a two-step synthesis procedure. The employed method allowed a lactam ring development of rhodamine-B and ethylenediamine to demonstrate a facile amide bond formation. The obtained RECM was confirmed by 1H NMR, 13C NMR, and mass spectrometry analysis. RECM was formed to detect copper ion (Cu2+ due to its problematic toxicity features in aquatic ecosystems. It showed a high selectivity toward Cu2+ in comparison with some environmentally relevant alkali, alkaline earth, and transition metal cations at 50 µM in acetonitrile. Moreover, non-fluorescent RECM showed fluorescence intensity and UV-Vis absorbance increases in the presence of Cu2+ with high linear dependent coefficients (R2 = 0.964 and R2 = 0.982 respectively as well as a color change from colorless to pink owing to the ring opening of the rhodamine spirolactam form. Binding capability experiments presented a clear 1:1 stoichiometry of RECM–Cu2+ complex with the binding constant (Ka as 2.25 × 104 M−1. The calculation of limits of detection (LOD was 0.21 µM based on the linear regression method, which is below the maximum contaminant level goal (MCLG value of Cu2+ (1.3 ppm equals to 20.46 µM in drinking water. These characteristics make the RECM a promising candidate for the real-time detection of toxic Cu2+ in environmental monitoring applications.

  19. Cu2Sb thin film electrodes prepared by pulsed laser deposition f or lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Song, Seung-Wan; Reade, Ronald P.; Cairns, Elton J.; Vaughey, Jack T.; Thackeray, Michael M.; Striebel, Kathryn A.

    2003-08-01

    Thin films of Cu2Sb, prepared on stainless steel and copper substrates with a pulsed laser deposition technique at room temperature, have been evaluated as electrodes in lithium cells. The electrodes operate by a lithium insertion/copper extrusion reaction mechanism, the reversibility of which is superior when copper substrates are used, particularly when electrochemical cycling is restricted to the voltage range 0.65-1.4 V vs. Li/Li+. The superior performance of Cu2Sb films on copper is attributed to the more active participation of the extruded copper in the functioning of the electrode. The continual and extensive extrusion of copper on cycling the cells leads to the isolation of Li3Sb particles and a consequent formation of Sb. Improved cycling stability of both types of electrodes was obtained when cells were cycled between 0.65 and 1.4 V. A low-capacity lithium-ion cell with Cu2Sb and LiNi0.8Co0.15Al0.05O2 electrodes, laminated from powders, shows excellent cycling stability over the voltage range 3.15 - 2.2 V, the potential difference corresponding to approximately 0.65-1.4 V for the Cu2Sb electrode vs. Li/Li+. Chemical self-discharge of lithiated Cu2Sb electrodes by reaction with the electrolyte was severe when cells were allowed to relax on open circuit after reaching a lower voltage limit of 0.1 V. The solid electrolyte interphase (SEI) layer formed on Cu2Sb electrodes after cells had been cycled between 1.4 and 0.65 V vs. Li/Li+ was characterized by Fourier-transform infrared spectroscopy; the SEI layer contributes to the large irreversible capacity loss on the initial cycle of these cells. The data contribute to a better understanding of the electrochemical behavior of intermetallic electrodes in rechargeable lithium batteries.

  20. CuO reduction induced formation of CuO/Cu2O hybrid oxides

    Science.gov (United States)

    Yuan, Lu; Yin, Qiyue; Wang, Yiqian; Zhou, Guangwen

    2013-12-01

    Reduction of CuO nanowires results in the formation of a unique hierarchical hybrid nanostructure, in which the parent oxide phase (CuO) works as the skeleton while the lower oxide (Cu2O) resulting from the reduction reaction forms as partially embedded nanoparticles that decorate the skeleton of the parent oxide. Using in situ transmission electron microscopy observations of the reduction process of CuO nanowires, we demonstrate that the formation of such a hierarchical hybrid oxide structure is induced by topotactic nucleation and growth of Cu2O islands on the parent CuO nanowires.

  1. Electron tunneling and the energy gap in Bi2Sr2CaCu2Ox

    Science.gov (United States)

    Lee, Mark; Mitzi, D. B.; Kapitulnik, A.; Beasley, M. R.

    1989-01-01

    Results of electron tunneling on single crystals of the Bi2Sr2CaCu2Ox superconductor are reported. The junctions show a gap structure with Δ~=25 meV, whose temperature dependence exhibits a qualitatively Bardeen-Cooper-Schrieffer-like behavior with a gap-closing Tc~=81-85 K. Comparisons of these tunneling spectra to those obtained on YBa2Cu3O7-x are made. Evidence that 2Δ/kTc~7 for both Ba2Sr2CaCu2Ox and YBa2Cu3O7-x is also discussed.

  2. EPR and optical studies of Cu2+ ions doped in magnesium potassium phosphate hexahydrate single crystals

    International Nuclear Information System (INIS)

    Kripal, Ram; Shukla, Santwana

    2011-01-01

    An electron paramagnetic resonance (EPR) study of Cu 2+ -doped magnesium potassium phosphate is performed at liquid nitrogen temperature (LNT; 77 K). Two magnetically non-equivalent sites for Cu 2+ are observed. The spin Hamiltonian parameters are determined with the fitting of spectra to a rhombic symmetry crystalline field. The ground state wavefunction is also determined. The g-anisotropy is evaluated and compared with the experimental value. With the help of an optical study, the nature of the bonding in the complex is discussed.

  3. Influence of Au Nanoparticle Shape on Au@Cu2O Heterostructures

    OpenAIRE

    Zhu, Jie; Lu, Na; Chen, Wei; Kong, Lina; Yang, Yun; Ma, Dekun; Huang, Shaoming

    2015-01-01

    Synthesis of metal-semiconductor heterostructures may allow the combination of function of the corresponding components and/or the enhanced performance resulting from the interactions between all the components. In this paper, Au@Cu2O core-shell heterostructures are prepared by a seed-growth method, using different-shaped Au nanocrystals as the seeds such as nanorods, octahedra, decahedra, dots, and nanocubes. The results revealed that the final structure of Au@Cu2O was greatly influenced by ...

  4. Derivation of Inter-Atomic Force Constants of Cu2O from Diffuse Neutron Scattering Measurement

    Directory of Open Access Journals (Sweden)

    T. Makhsun

    2013-04-01

    Full Text Available Neutron scattering intensity from Cu2O compound has been measured at 10 K and 295 K with High Resolution Powder Diffractometer at JRR-3 JAEA. The oscillatory diffuse scattering related to correlations among thermal displacements of atoms was observed at 295 K. The correlation parameters were determined from the observed diffuse scattering intensity at 10 and 295 K. The force constants between the neighboring atoms in Cu2O were estimated from the correlation parameters and compared to those of Ag2O

  5. Ultra-thin Cu2ZnSnS4 solar cell by pulsed laser deposition

    DEFF Research Database (Denmark)

    Cazzaniga, Andrea Carlo; Crovetto, Andrea; Yan, Chang

    2017-01-01

    We report on the fabrication of a 5.2% efficiency Cu2ZnSnS4 (CZTS) solar cell made by pulsed laser deposition (PLD) featuring an ultra-thin absorber layer (less than 450 nm). Solutions to the issues of reproducibility and micro-particulate ejection often encountered with PLD are proposed. At the ......We report on the fabrication of a 5.2% efficiency Cu2ZnSnS4 (CZTS) solar cell made by pulsed laser deposition (PLD) featuring an ultra-thin absorber layer (less than 450 nm). Solutions to the issues of reproducibility and micro-particulate ejection often encountered with PLD are proposed...

  6. High field superconducting magnets

    Science.gov (United States)

    Hait, Thomas P. (Inventor); Shirron, Peter J. (Inventor)

    2011-01-01

    A superconducting magnet includes an insulating layer disposed about the surface of a mandrel; a superconducting wire wound in adjacent turns about the mandrel to form the superconducting magnet, wherein the superconducting wire is in thermal communication with the mandrel, and the superconducting magnet has a field-to-current ratio equal to or greater than 1.1 Tesla per Ampere; a thermally conductive potting material configured to fill interstices between the adjacent turns, wherein the thermally conductive potting material and the superconducting wire provide a path for dissipation of heat; and a voltage limiting device disposed across each end of the superconducting wire, wherein the voltage limiting device is configured to prevent a voltage excursion across the superconducting wire during quench of the superconducting magnet.

  7. Understanding and application of superconducting materials

    International Nuclear Information System (INIS)

    Moon, Byeong Mu; Lee, Chun Heung

    1997-02-01

    This book deals with superconducting materials, which contains from basic theory to application of superconducting materials. The contents of this book are mystery of superconducting materials, properties of superconducting materials, thermodynamics of superconducting materials, theoretical background of superconducting materials, tunnelling and quantum interference, classification and properties of superconducting materials, high temperature superconducting materials, production and analysis of superconducting materials and application of superconducting materials.

  8. Excellent photocatalytic hydrogen production over CdS nanorods via using noble metal-free copper molybdenum sulfide (Cu2MoS4) nanosheets as co-catalysts

    Science.gov (United States)

    Hong, Sangyeob; Kumar, D. Praveen; Reddy, D. Amaranatha; Choi, Jiha; Kim, Tae Kyu

    2017-02-01

    Charge carrier recombination and durability issues are major problems in photocatalytic hydrogen (H2) evolution processes. Thus, there is a very important necessitate to extend an efficient photocatalyst to control charge-carrier dynamics in the photocatalytic system. We have developed copper molybdenum sulfide (Cu2MoS4) nanosheets as co-catalysts with CdS nanorods for controlling charge carriers without recombination for use in photocatalytic H2 evolution under simulated solar light irradiation. Effective control and utilization of charge carriers are possible by loading Cu2MoS4 nanosheets onto the CdS nanorods. The loading compensates for the restrictions of CdS, and stimulated synergistic effects, such as efficient photoexcited charge separation, lead to an improvement in photostability because of the layered structure of the Cu2MoS4nanosheets. These layered Cu2MoS4 nanosheets have emerged as novel and active replacements for precious noble metal co-catalysts in photocatalytic H2 production by water splitting. We have obtained superior H2 production rates by using Cu2MoS4 loaded CdS nanorods. The physicochemical properties of the composites are analyzed by diverse characterization techniques.

  9. LaNiO3 buffer layers for high critical current density YBa2Cu3O7-δ and Tl2Ba2CaCu2O8-δ films

    International Nuclear Information System (INIS)

    Carlson, C.M.; Parilla, P.A.; Siegal, M.P.; Ginley, D.S.; Wang, Y.; Blaugher, R.D.; Price, J.C.; Overmyer, D.L.; Venturini, E.L.

    1999-01-01

    We demonstrate high critical current density superconducting films of YBa 2 Cu 3 O 7-δ (YBCO) and Tl 2 Ba 2 CaCu 2 O 8-δ (Tl-2212) using LaNiO 3 (LNO) buffer layers. YBCO films grown on an LNO buffer layer have only a slightly lower J c (5 K, H=0) than films grown directly on a bare LaAlO 3 substrate. YBCO films grown on LNO buffer layers exhibit minor microstructural disorder and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reductions in J c at all temperatures and fields compared to those grown on bare LaAlO 3 , correlating to both a-axis grain and nonsuperconducting phase formation. LNO could be a promising buffer layer for both YBCO and Tl-based superconducting films in coated conductor applications. copyright 1999 American Institute of Physics

  10. LaNiO3 Buffer Layers for High Critical Current Density YBa2Cu3O7δ and Tl2Ba2CaCu2O8δ Films

    International Nuclear Information System (INIS)

    Carlson, C.M.; Parilla, P.A.; Siegal, M.P.; Ginley, D.S.; Wang, Y.-T.; Blaugher, R.D.; Price, J.C.; Overmyer, D.L.; Venturini, E.L.

    1999-01-01

    We demonstrate high critical current density superconducting films of YBa 2 Cu 3 O 7-δ (YBCO) and Tl 2 Ba 2 CaCu 2 O 8-δ (Tl-2212) using LaNiO 3 (LNO) buffer layers. YBCO films grown on an LNO buffer layer have only a slightly lower J c (5K, H=0) than films grown directly on a bare LaAlO 3 substrate. It is noteworthy that YBCO films grown on LNO buffer layers exhibit minor microstructural disorder and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reductions in J c at all temperatures and fields compared to those grown on bare LaAlO 3 , correlating to both a-axis grain and nonsuperconducting phase formation. With additional optimization, LNO could be a promising buffer layer for both YBCO and Tl-based superconducting films, perhaps ideally suited for coated conductor applications

  11. High-resolution angle-resolved photoemission studies of high Tc superconductor Bi2Sr2CaCu2O8

    International Nuclear Information System (INIS)

    Liu, Rong.

    1990-01-01

    An angle-resolved photoemission study of the normal and superconducting states in Bi 2 Sr 2 CaCu 2 O 8 was performed. Measurements in the normal state show bands dispersing through the Fermi level from at least 350 meV below E F . The Fermi level crossings are consistant with local-density band calculation, including a point calculated to be of Bi-O character. Additional measurements were made where bands crossed the Fermi level between 100 and 250K, along with measurements on an adjacent Pt foil. The Fermi edges of both materials agree to within the noise. Below the Fermi level, the spectra show correlation effects on the form of an increased effective mass. The shape of the spectra can be explained by a lifetime-broadened photohole and secondary electrons. The effective inverse photohole lifetime is linear in energy. A superconducting gap has been measured at a number of points where there is density at the Fermi level in the normal state. By proper modeling, a gap of 24 meV was obtained for all these points, including points of Cu-O and Bi-O character respectively, according to band calculation. The lack of gap anisotropy in the basal plane suggests that pinning in this material is not d-wave pairing

  12. Thick Bi2Sr2CaCu2O8+δ films grown by liquid-phase epitaxy for Josephson THz applications

    Science.gov (United States)

    Simsek, Y.; Vlasko-Vlasov, V.; Koshelev, A. E.; Benseman, T.; Hao, Y.; Kesgin, I.; Claus, H.; Pearson, J.; Kwok, W.-K.; Welp, U.

    2018-01-01

    Theoretical and experimental studies of intrinsic Josephson junctions (IJJs) that naturally occur in high-T c superconducting Bi2Sr2CaCu2O8+δ (Bi-2212) have demonstrated their potential for novel types of compact devices for the generation and sensing of electromagnetic radiation in the THz range. Here, we show that the THz-on-a-chip concept may be realized in liquid-phase epitaxial-grown (LPE) thick Bi-2212 films. We have grown μm thick Bi-2212 LPE films on MgO substrates. These films display excellent c-axis alignment and single crystal grains of about 650 × 150 μm2 in size. A branched current-voltage characteristic was clearly observed in c-axis transport, which is a clear signature of underdamped IJJs, and a prerequisite for THz-generation. We discuss LPE growth conditions allowing improvement of the structural quality and superconducting properties of Bi-2212 films for THz applications.

  13. Ruthenocuprats: Playground for superconductivity and magnetism

    Directory of Open Access Journals (Sweden)

    A. Khajehnezhad

    2008-03-01

    Full Text Available  We have compared the structural, electrical, and magnetic properties of Ru(Gd1.5-xPrxCe0.5Sr2Cu2O10-δ (Pr/Gd samples with x = 0.0, 0.01, 0.03, 0.033, 0.035, 0.04, 0.05, 0.06, 0.1 and RuGd1.5(Ce0.5-xPrxSr2Cu2O10-δ (Pr/Ce samples with x = 0.0, 0.01, 0.03, 0.05, 0.08, 0.1, 0.15, 0.2 prepared by the standard solid-state reaction technique with RuGd1.5(GdxCe0.5-x Sr2Cu2O10-δ (Gd/Ce samples with x= 0.0, 0.1, 0.2, 0.3. We obtained the XRD patterns for different samples with various x. The lattice parameters versus x for different substitutions have been obtained from the Rietveld analysis. To determine how the magnetic and superconducting properties of these layered cuprate systems can be affected by Pr substitution, the resistivity and magnetoresistivity, with Hext varying from 0.0 to 15 kOe, have been measured at various temperatures. Superconducting transition temperature Tc and magnetic transition Tirr have been obtained through resistivity and ac susceptibility measurements. The Tc suppression due to Gd/Ce, Pr/Gd and Pr/Ce substitutions show competition between pair breaking by magnetic impurity, hole doping due to different ionic valences, difference in ionic radii, and oxygen stoichiometry. Pr/Gd substitution suppresses superconductivity more rapidly than for Pr/Ce or Gd/Ce, showing that the effect of hole doping and pair breaking by magnetic impurity is stronger than the difference in ionic radii. In Pr/Gd substitution, the small difference between the ionic radii of Pr and Gd, and absorption of more oxygen due to higher valence of Pr with respect to Gd, decrease the mean Ru-Ru distance, and as a result, the magnetic exchange interaction becomes stronger with the increase of x. But, Pr/Ce and Gd/Ce substitutions have a reverse effect. The magnetic properties such as Hc, obtained through magnetization measurements versus applied magnetic field isoterm at 77K and room temperatures, become stronger with x in Pr/Gd and weaker with x in Pr

  14. Preparation and electrochemical performances of cubic shape Cu2O as anode material for lithium ion batteries

    International Nuclear Information System (INIS)

    Zhang, C.Q.; Tu, J.P.; Huang, X.H.; Yuan, Y.F.; Chen, X.T.; Mao, F.

    2007-01-01

    Cubic and star-shaped crystalline Cu 2 O particles were synthesized by reducing the copper citrate complex solution with glucose. The microstructure and morphology of the Cu 2 O were characterized by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical properties of the Cu 2 O as anode materials for lithium ion batteries were measured by galvanostatic charge-discharge tests. The as-synthesized Cu 2 O particles were 1-2 μm with narrow distribution and the shape of Cu 2 O particles had an effect on the electrochemical properties. The cubic Cu 2 O particles delivered a higher reversible discharge capacity (390 mAh g -1 ) than the star-shaped Cu 2 O, and also exhibited good cyclability. The star-shaped Cu 2 O particles presented poor cyclability due to pulverization and deterioration after cycling, but the morphology of the cubic Cu 2 O particles was stable even after 50 cycles

  15. Fermi surface investigation in the scanning tunneling microscopy of Bi2Sr2CaCu2O8

    International Nuclear Information System (INIS)

    Voo, K.K.; Wu, W.C.; Chen, H.Y.; Mou, C.Y.

    2004-01-01

    Within the ideal Fermi liquid picture, the impurity-induced spatial modulation of local density of states (LDOS) in the d-wave superconductor Bi 2 Sr 2 CaCu 2 O 8 is investigated at different superconducting (SC) gap sizes. These LDOS spectra are related to the finite-temperature dI/dV spectra in scanning tunneling microscopy (STM), when the Fermi distribution factor is deconvoluted away from dI/dV. We find stripe-like structures even in the zero gap case due to a local-nesting mechanism. This mechanism is different from the octet-scattering mechanism in the d-wave SC (dSC) state proposed by McElroy et al. [K. McElroy, R.W. Simmonds, J.E. Hoffman, D.H. Lee, J. Orenstein, H. Eisaki, S. Uchida, J.C. Davis, Nature 422 (2003) 592]. The zero gap LDOS is related to the normal state dI/dV. The zero gap spectra when Fourier-transformed into the reciprocal space, can reveal the information of the entire Fermi surface at a single measuring bias voltage, in contrast to the point-wise tracing out proposed by McElroy et al. This may serve as another way to check the reality of Landau quasiparticles in the normal state. We have also re-visited the octet-scattering mechanism in the dSC state and pointed out that, due to the Umklapp symmetry, there are additional peaks in the reciprocal space that experimentally yet to be found

  16. Ultrathin Cu2O as an efficient inorganic hole transporting material for perovskite solar cells

    KAUST Repository

    Yu, Weili; Li, Feng; Wang, Hong; Alarousu, Erkki; Chen, Yin; Lin, Bin; Wang, Lingfei; Hedhili, Mohamed N.; Li, Yangyang; Wu, Kewei; Wang, Xianbin; Mohammed, Omar F.; Wu, Tao

    2016-01-01

    We demonstrate that ultrathin P-type Cu2O thin films fabricated by a facile thermal oxidation method can serve as a promising hole-transporting material in perovskite solar cells. Following a two-step method, inorganic-organic hybrid perovskite

  17. Stability of sputter deposited cuprous oxide (Cu2O) subjected to ageing conditions for photovoltaic applications

    Science.gov (United States)

    Camacho-Espinosa, E.; Rimmaudo, I.; Riech, I.; Mis-Fernández, R.; Peña, J. L.

    2018-02-01

    Among various metal oxide p-type semiconductors, cuprous oxide (Cu2O) stands out as a nontoxic and abundant material, which also makes it a suitable candidate as a low-cost absorber for photovoltaic applications. However, the chemical stability of the absorber layer is critical for the solar cell lifetime, in particular, for Cu-based materials, concerning to its oxidation state changes. In this paper, we addressed the Cu2O stability depositing films of 170 nm by reactive radio frequency magnetron sputtering and subsequently ageing them in conditions similar to the typical accelerated life test for the solar module, in a period of time from one to five weeks. The stability of the optical, electrical, and structural properties of the Cu2O thin films was investigated using UV-VIS-near infrared transmittance, 4-probes electrical resistance characterization, high precision profilometry, X-ray photoelectron spectroscopy, and grazing incidence X-ray diffraction. Finally, we demonstrated that the aging tests affected only the surface of the films, while the bulk remained unaltered, making Cu2O a promising candidate for production of stable devices, including solar cells.

  18. Cu(2+) and Fe(2+) mediated photodegradation studies of soil-incorporated chlorpyrifos.

    Science.gov (United States)

    Rafique, Nazia; Tariq, Saadia R; Ahad, Karam; Taj, Touqeer

    2016-03-01

    The influences of Cu(2+) and Fe(2+) on the photodegradation of soil-incorporated chlorpyrifos were investigated in the present study. The soil samples spiked with chlorpyrifos and selected metal ions were irradiated with UV light for different intervals of time and analyzed by HPLC. The unsterile and sterile control soil samples amended with pesticides and selected metals were incubated in the dark at 25 °C for the same time intervals. The results of the study evidenced that photodegradation of chlorpyrifos followed the first-order kinetics. The dissipation t0.5 of chlorpyrifos was found to decrease from 41 to 20 days under UV irradiation. The rate of chlorpyrifos photodegradation was increased in the presence of both metals, i.e., Cu(2+) and Fe(2+). Thus, initially observed t0.5 of 19.8 days was decreased to 4.39 days in the case of Cu(+2) and 19.25 days for Fe(+2). Copper was found to increase the rate of photodegradation by 4.5 orders of magnitude while the microbial degradation of chlorpyrifos was increased only twofold. The microbial degradation of chlorpyrifos was only negligibly affected by Fe(2+) amendment. The studied trace metals also affected the abiotic degradation of the pesticide in the order Cu(2+) > Fe(2+).

  19. Thermal expansion of the heavy-fermion compound CeInCu2 at high pressure

    International Nuclear Information System (INIS)

    Kagayama, Tomoko; Oomi, Gendo; Onuki, Yoshichika; Komatsubara, Takemi

    1994-01-01

    The thermal expansion coefficient α of the heavy-fermion compound CeInCu 2 has been measured at high pressure up to 2 GPa in the temperature range from 6 to 300 K. It is found that the linear term in α(T) at low temperature decreases by the application of pressure. ((orig.))

  20. Adsorption of Cu 2+ , As 3+ and Cd 2+ ions from aqueous solution ...

    African Journals Online (AJOL)

    The adsorption of Cu2+, Cd2+ and As3+ ions on eggshell from aqueous solution was studied under batch conditions at 30, 40, 50 and 60oC and concentrations of 10, 20, 30, 60 and 80 mg/l. The partition coefficient for the ions between aqueous solution and chicken eggshell increased with time and with increase in the ...

  1. Thermodynamic studies on the adsorption of Cu2+, Ni2+ and Cd2+ ...

    African Journals Online (AJOL)

    Amine-modified bentonite (TEPA-Bn) has been prepared with tetraethylenepentamine (TEPA) as a modifier. The structure of Ca-based bentonite (Ca-Bn), TEPA-Bn and TEPA-Bn after adsorbing Cu2+,Ni2+,Cd2+ had been characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and ...

  2. Prospects of chemically deposited CoS-CU2S coatings for solar ...

    African Journals Online (AJOL)

    The thin films of Cu2S deposited on CoS-precoated glass substrates from chemical baths and annealed at 100oC were found to have desirable solar control characteristics superior to commercial tinted glass and magnetron sputtered multilayer metallic solar control coatings. These include: transmission spectra in the ...

  3. Antibacterial studies of novel Cu2WS4 ternary chalcogenide synthesized by hydrothermal process

    Science.gov (United States)

    Kannan, Selvaraj; Vinitha, Perumal; Mohanraj, Kannusamy; Sivakumar, Ganesan

    2018-02-01

    This is the first report for the synthesis of L-cysteine mediated Cu2WS4 nanoparticles for different temperatures by an inexpensive and less pollutive hydrothermal method. The as-synthesized particles were characterized by XRD, FTIR, FESEM, UV-vis diffuse reflectance and PL spectra technique respectively. The phase purity and structural confirmation were studied by X-ray powder diffraction technique. It is observed that the synthesis temperature affecting the crystalline size. The optical analysis of the Cu2WS4 nanoparticles showed direct band gap in the range of 2.1-2.3 eV. The intensity of the PL emission spectra decreases with increase of reaction temperature. The antibacterial performance of Cu2WS4 nanoparticles were investigated by agar well diffusion method and the results confirm that the antibacterial activity of Cu2WS4 against Gram-positive (B. subtilis, M. luteus) and Gram-negative (E. coli, P. aeruginosa and K. pneumoniae) bacteria.

  4. Multi-branched Cu2O nanowires for photocatalytic degradation of methyl orange

    Science.gov (United States)

    Yu, Chunxin; Shu, Yun; Zhou, Xiaowei; Ren, Yang; Liu, Zhu

    2018-03-01

    Multi-branched cuprous oxide nanowires (Cu2O NWs) were prepared by one-step hydrothermal method of a facile process. The architecture of these Cu2O NWs was examined by scanning electron microscopy, and the resulting crystal nanowire consists of the trunk growing along [100] plane and the branch growing along [110] plane. Photocatalytic degradation of methyl orange (MO) in the experiment indicates that pure Cu2O NWs prepared at 150 °C have a higher photocatalytic activity (90% MO were degraded within 20 min without the presence of H2O2) compared with the samples obtained at other temperatures. In the photoelectrochemical test, pure Cu2O NWs had outstanding photoelectric response, which corresponds to the catalytic performance. The superior photocatalytic performance can be attributed to the absence of grain boundaries between the small branches and the nanowire trunk, which is conducive to the transport of photo-generated carriers, and the reduction of Cu impurities to reduce the number of recombination centers.

  5. Cooper pair formation dynamics in Bi2Sr2CaCu2O8+δ

    International Nuclear Information System (INIS)

    Kaindl, R.A.; Carnahan, M.A.; Orenstein, J.; Chemla, D.S.; Oh, S.; Eckstein, J.N.

    2003-01-01

    We utilize ultrafast terahertz pulses to monitor the carrier dynamics in the high-TC superconductor Bi2Sr2CaCu2O8+delta. The temperature, density and time dependence distinctly exposes a bimolecular recombination process of quasiparticles which underlies formation of Cooper pairs

  6. Highly sensitive and selective fluorescent assay for guanine based on the Cu(2+)/eosin Y system.

    Science.gov (United States)

    Shi, Huimin; Cui, Yi; Gong, Yijun; Feng, Suling

    2016-05-15

    A fluorescent probe has been developed for the determination of guanine based on the quenched fluorescence signal of Cu(2+)/eosin Y. Cu(2+) interacted with eosin Y, resulting in fluorescence quenching. Subsequently, with the addition of guanine to the Cu(2+)/eosin Y system, guanine reacted with Cu(2+) to form 1:1 chelate cation, which further combined with eosin Y to form a 1:1 ternary ion-association complex by electrostatic attraction and hydrophobic interaction, resulting in significant decrease of the fluorescence. Hence, a fluorescent system was constructed for rapid, sensitive and selective detection of guanine with a detection limit as low as 1.5 nmol L(-1) and a linear range of 3.3-116 nmol L(-1). The method has been applied satisfactorily to the determination of guanine in DNA and urine samples with the recoveries from 98.7% to 105%. This study significantly expands the realm of application of ternary ion-association complex in fluorescence probe. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Highly sensitive and selective fluorescent assay for guanine based on the Cu2 +/eosin Y system

    Science.gov (United States)

    Shi, Huimin; Cui, Yi; Gong, Yijun; Feng, Suling

    2016-05-01

    A fluorescent probe has been developed for the determination of guanine based on the quenched fluorescence signal of Cu2 +/eosin Y. Cu2 + interacted with eosin Y, resulting in fluorescence quenching. Subsequently, with the addition of guanine to the Cu2 +/eosin Y system, guanine reacted with Cu2 + to form 1:1 chelate cation, which further combined with eosin Y to form a 1:1 ternary ion-association complex by electrostatic attraction and hydrophobic interaction, resulting in significant decrease of the fluorescence. Hence, a fluorescent system was constructed for rapid, sensitive and selective detection of guanine with a detection limit as low as 1.5 nmol L- 1 and a linear range of 3.3-116 nmol L- 1. The method has been applied satisfactorily to the determination of guanine in DNA and urine samples with the recoveries from 98.7% to 105%. This study significantly expands the realm of application of ternary ion-association complex in fluorescence probe.

  8. Giant Cu 2p Resonances in CuO Valence-Band Photoemission

    NARCIS (Netherlands)

    Tjeng, L.H.; Chen, C.T.; Ghijsen, J.; Rudolf, P.; Sette, F.

    1991-01-01

    We report the observation of a giant resonance in the Cu 2p resonant-photoemission spectra of CuO. The study allows the unambiguous identification of the local Cu 3d8 configuration in the valence-band photoemission spectrum, providing conclusive evidence for the charge-transfer nature of the

  9. Adsorption of Cu 2+ and Ni 2+ ions from their aqueous solutions ...

    African Journals Online (AJOL)

    The adsorption of Cu2+ and Ni2+ions at room temperature (27°C) onto two types of biomass produced from orange mesocarp namely: untreated orange mesocarp (Me) of 250 μm particle size and xanthated orange mesocarp (XMe) produced from Me of 250 μm particle size were studied. The results obtained showed that ...

  10. Cu2+1O coated polycrystalline Si nanoparticles as anode for lithium-ion battery.

    Science.gov (United States)

    Zhang, Junying; Zhang, Chunqian; Wu, Shouming; Liu, Zhi; Zheng, Jun; Zuo, Yuhua; Xue, Chunlai; Li, Chuanbo; Cheng, Buwen

    2016-12-01

    Cu2+1O coated Si nanoparticles were prepared by simple hydrolysis and were investigated as an anode material for lithium-ion battery. The coating of Cu2+1O on the surface of Si particles remarkably improves the cycle performance of the battery than that made by the pristine Si. The battery exhibits an initial reversible capacity of 3063 mAh/g and an initial coulombic efficiency (CE) of 82.9 %. With a current density of 300 mA/g, its reversible capacity can remains 1060 mAh/g after 350 cycles, corresponding to a CE ≥ 99.8 %. It is believed that the Cu2+1O coating enhances the electrical conductivity, and the elasticity of Cu2+1O further helps buffer the volume changes during lithiation/delithiation processes. Experiment results indicate that the electrode maintained a highly integrated structure after 100 cycles and it is in favour of the formation of stable solid electrolyte interface (SEI) on the Si surface to keep the extremely high CE during long charge and discharge cycles.

  11. Low-temperature thermoelectric properties of Pb doped Cu2SnSe3

    Science.gov (United States)

    Prasad K, Shyam; Rao, Ashok; Gahtori, Bhasker; Bathula, Sivaiah; Dhar, Ajay; Chang, Chia-Chi; Kuo, Yung-Kang

    2017-09-01

    A series of Cu2Sn1-xPbxSe3 (0 ≤ x ≤ 0.04) compounds was prepared by solid state synthesis technique. The electrical resistivity (ρ) decreased with increase in Pb content up to x = 0.01, thereafter it increased with further increase in x (till x = 0.03). However, the lowest value of electrical resistivity is observed for Cu2Sn0.96Pb0.04Se3. Analysis of electrical resistivity of all the samples suggests that small poloron hoping model is operative in the high temperature regime while variable range hopping is effective in the low temperature regime. The positive Seebeck coefficient (S) for pristine and doped samples in the entire temperature range indicates that the majority charge carriers are holes. The electronic thermal conductivity (κe) of the Cu2Sn1-xPbxSe3 compounds was estimated by the Wiedemann-Franz law and found that the contribution from κe is less than 1% of the total thermal conductivity (κ). The highest ZT 0.013 was achieved at 400 K for the sample Cu2Sn0.98Pb0.02Se3, about 30% enhancement as compared to the pristine sample.

  12. Biosorption of Pb2+ and Cu2+ in aqueous solutions using agricultural wastes

    Directory of Open Access Journals (Sweden)

    Nieva Aileen D.

    2017-01-01

    Full Text Available This study aimed to determine and compare the adsorptive capacity of Pb2+ and Cu2+ in simulated wastewater onto three agricultural wastes The adsorption capacities of Pb2+ onto the agricultural wastes can be arranged as Litchi chinensis (4.30 mg of sorbate per g of sorbent (mg g-1, 85.68% adsorption > Bambusa vulgaris (3.83 mg g-1, 76.19% adsorption > Annona squamosa (2.70 mg g-1, 53.66% adsorption while the adsorption capacities of Cu2+ onto the same agricultural wastes can be arranged in the order: Bambusa vulgaris (3.86 mg g-1, 77.17% adsorption > Annona squamosal (3.58 mg g-1, 71.58% adsorption > Litchi chinensis (3.42 mg g-1, 68.32% adsorption. The biosorbents had relatively higher adsorptive capacities with Cu2+ as compared to that of Pb2+ except for Litchi chinensis. Although the results show lower adsorptive capacity as compared to a number of treated agricultural wastes showing 80% up to almost 100% adsorption of Pb2+ and Cu2+, the results show that Annona squamosa, Bamubusa vulgaris, and Litchi chinensis are potential biosorbents and promote sustainable treatment process.

  13. Assessment of the relative toxicity of Cu2+ by measuring structural changes of supercoiled DNA

    International Nuclear Information System (INIS)

    Pan Gang; Chang Guohua; Chen Hao; Giusti, Lorenzo

    2007-01-01

    A method for the measurement of the relative toxicity of Cu 2+ in aquatic environments is proposed. It is based on the quantitative measurement on the shape change of the supercoiled DNA after it is contacted with different levels of Cu 2+ for various time intervals. In the absence of any redox reagents, all supercoiled DNA degraded into other forms of DNA after 24 h incubation in the presence of 5.13 x 10 -3 , 5.08 x 10 -4 and 5.35 x 10 -5 mol/L Cu 2+ . At a lower Cu 2+ concentration (10 -6 mol/L), 44% of supercoiled DNA retained its original supercoiled form after 24 h, and 29% after 48 h. The concentration of RC 50 , i.e. concentration of pollutants at which 50% of the supercoiled DNA was relaxed compared to control samples, can be obtained from the does-response curves at different exposure time, which may provide a rapid and convenient approach to assess the relative toxicity of environmental pollutants. - RC 50 values (concentration at which 50% of the supercoiled DNA relaxed) can be used to reflect the relative toxicity of Cu in aquatic environment

  14. The effect of silica concentration on the biosorption of Cu2+ and ...

    African Journals Online (AJOL)

    2009-10-26

    Oct 26, 2009 ... The effects of pH, contact time, initial ion concentration and the ... from solutions of low concentration (0.002 M and 0.07 M) than from solutions of high concentration (0.2 M) over ... Pollution of the environment with heavy metals, mainly as a ..... 2 metal ions; although the charges on both Cu2+ and Co2+.

  15. Impacts of EDTA on Uptake and Accumulation of Cu2+ by Spinach ...

    African Journals Online (AJOL)

    MBI

    2017-06-05

    Jun 5, 2017 ... INTRODUCTION. Copper is an essential micronutrient in plants. It plays a significant ... reactive oxygen species (ROS) and free radicals. (Erdei et al., 2002; .... higher levels of applied Cu2+ enhanced the uptake of the ion by ...

  16. Diffuse neutron scattering study of Cu2−xSe

    DEFF Research Database (Denmark)

    Cava, R. J.; Andersen, Niels Hessel; Clausen, Kurt Nørgaard

    1986-01-01

    We have measured the diffuse neutron scattering in the hkk plane for Cu2Se and Cu1.8Se at 180°C and 51°C, respectively, in the cubic antifluorite type phase. The diffuse scattering shows significant structure, indicative of correlated short range mobile ion ordering. The short range order is foun...

  17. Humidity sensing performance of in-situ fabricated Cu/Cu2O/Cu2S-polymer nanocomposite via polyphenylene sulphide cyclisation route.

    Science.gov (United States)

    Adkar, Dattatraya; Hake, Abhay; Jadkar, Sandesh; Adhyapak, Parag; Mulik, Uttamrao; Amalnerkar, Dinesh

    2011-08-01

    We herein report the feasibility of novel polymer-inorganic solid state reaction route for simultaneous in situ generation of Cu2S and Cu nanostructures in polymer network. Polyphenylene Sulphide (PPS) which is engineering thermoplastic acts as chalcogen source as well as stabilizing matrix for the resultant nano products. Typical solid state reaction was accomplished by simply heating the physical admixtures of the two reactants i.e., copper acetate and PPS by varying molar ratios mainly 1:1, 1:5, 1:10, 1:15, 1:20 at the crystalline melting temperature (285 degrees C) of PPS. The synthesized products were characterized using various physicochemical characterization techniques like X-ray Diffractometry, Field emission Scanning Electron Microscopy, Transmission Electron Microscopy, UV-Visible spectroscopy and X-ray photoelectron spectroscopy. The prima facie observations suggest occurrence of nanocrystalline Cu2S in case of product obtained with equimolar ratio, whereas remaining samples show mixture of Cu and Cu2O. The TEM analysis reveals nanoscale polydispersity (5-60 nm) and prevalence of mainly spherical morphological features in all the cases with occasional indications of plate like and cubical morphological features depending upon the molar ratio of the reactants. The humidity sensing characterization of these nanocomposites was also performed. The resistivity response with the level of humidity (20 to 70% RH) was compared for these nanocomposites. The linear response is obtained for all the samples. The sensitivity of 1:1 molar ratio sample was found to be maximum among all the samples.

  18. Crystal structure determination of solar cell materials: Cu2ZnSnS4 thin films using X-ray anomalous dispersion

    International Nuclear Information System (INIS)

    Nozaki, Hiroshi; Fukano, Tatsuo; Ohta, Shingo; Seno, Yoshiki; Katagiri, Hironori; Jimbo, Kazuo

    2012-01-01

    Highlights: ► Cu 2 ZnSnS 4 thin films as a solar cell material were synthesized. ► The wavelength dependences of the diffraction intensity were measured. ► The crystal structures were clearly identified as kesterite structure for all samples. ► Crystal structure analysis revealed that the atomic compositions were Cu/(Zn + Sn) = 0.97 and Zn/Sn = 1.42 for the sample synthesized using stoichiometric amount of starting materials. - Abstract: The crystal structure of Cu 2 ZnSnS 4 (CZTS) thin films fabricated by vapor-phase sulfurization was determined using X-ray anomalous dispersion. High statistic synchrotron radiation X-ray diffraction data were collected from very small amounts of powder. By analyzing the wavelength dependencies of the diffraction peak intensities, the crystal structure was clearly identified as kesterite. Rietveld analysis revealed that the atomic composition deviated from stoichiometric composition, and the compositions were Cu/(Zn + Sn) = 0.97, and Zn/Sn = 1.42.

  19. The Triple Roles of Glutathione for a DNA-Cleaving DNAzyme and Development of a Fluorescent Glutathione/Cu2+-Dependent DNAzyme Sensor for Detection of Cu2+ in Drinking Water.

    Science.gov (United States)

    Wang, Shijin; Liu, Chengcheng; Li, Guiying; Sheng, Yongjie; Sun, Yanhong; Rui, Hongyue; Zhang, Jin; Xu, Jiacui; Jiang, Dazhi

    2017-03-24

    Pistol-like DNAzyme (PLDz) is an oxidative DNA-cleaving catalytic DNA with ascorbic acid as cofactor. Herein, glutathione was induced into the reaction system to maintain reduced ascorbic acid levels for higher efficient cleavage. However, data indicated that glutathione played triple roles in PLDz-catalyzed reactions. Glutathione alone had no effect on PLDz, and showed inhibitory effect on ascorbic acid-induced PLDz catalysis, but exhibited stimulating effect on Cu 2+ -promoted self-cleavage of PLDz. Further analysis of the effect of glutathione/Cu 2+ on PLDz indicated that H 2 O 2 played a key role in PLDz catalysis. Finally, we developed a fluorescent Cu 2+ sensor (PL-Cu 1.0) based on the relationship between glutathione/Cu 2+ and catalytic activity of PLDz. The fluorescent intensity showed a linear response toward the logarithm concentration of Cu 2+ over the range from 80 nM to 30 μM, with a detection limit of 21.1 nM. PL-Cu 1.0 provided only detection of Cu 2+ over other divalent metal ions. Ca 2+ and Mg 2+ could not interfere with Cu 2+ detection even at a 1000-fold concentration. We further applied PL-Cu 1.0 for Cu 2+ detection in tap and bottled water. Water stored in copper taps overnight had relatively high Cu 2+ concentrations, with a maximum 22.3 μM. Trace Cu 2+ (52.2 nM) in deep spring was detected among the tested bottled water. Therefore, PL-Cu 1.0 is feasible to detect Cu 2+ in drinking water, with a practical application.

  20. Development of Nb-Ti multifilamentar superconducting wires

    International Nuclear Information System (INIS)

    Otubo, J.

    1986-01-01

    Ni-Ti superconducting wires with multifilamentar configuration were produced, using the grouping technique. Some basic concepts on superconductivity and its main critical parameters are presented. The criteria for stabilizing superconductors in terms of the geometry are studied. The main critical parameters, H c , J c , T c in function of the composition and the metallurgical structure of Ni-Ti alloy are analysed. The development of Ni-Ti superconducting wires is described. (M.C.K.) [pt

  1. Electronic structure of TlBa2CaCu2O7-δ

    Science.gov (United States)

    Vasquez, R. P.; Novikov, D. L.; Freeman, A. J.; Siegal, M. P.

    1997-06-01

    The core levels of TlBa2CaCu2O7-δ (Tl-1212) epitaxial films have been measured with x-ray photoelectron spectroscopy (XPS). The valence electronic structure has been determined using the full-potential linear muffin-tin-orbital band-structure method and measured with XPS. The calculations show that a van Hove singularity (VHS) lies above the Fermi level (EF) for the stoichiometric compound (δ=0), while for 50% oxygen vacancies in the Tl-O layer (δ=0.5) EF is in close proximity to the VHS. Samples annealed in nitrogen (to reduce the hole overdoping by the removal of oxygen) exhibit higher core-level binding energies and a higher Tc, consistent with a shift of EF closer to the VHS. Comparisons are made to the core levels and valence bands of Tl2Ba2CaCu2O8+δ (Tl-2212) and HgBa2CaCu2O6+δ (Hg-1212). The similarity of the Cu 2p3/2 spectra for Tl-1212 and Tl-2212 indicates that the number of Tl-O layers has little effect on the Cu-O bonding. However, the Tl-1212 and Hg-1212 Cu 2p3/2 signals exhibit differences which suggest that the replacement of Tl3+ with Hg2+ results in a decrease in the O 2p-->Cu 3d charge-transfer energy and differences in the probabilities of planar vs apical oxygen charge transfer and/or Zhang-Rice singlet-state formation. Differences between the Tl-1212 and the Tl-2212 and Hg-1212 measured valence bands are consistent with the calculated Cu 3d and (Tl,Hg) 6s/5d partial densities of states.

  2. Electronic structure of TlBa2CaCu2O7-δ

    International Nuclear Information System (INIS)

    Vasquez, R.P.; Novikov, D.L.; Freeman, A.J.; Siegal, M.P.

    1997-01-01

    The core levels of TlBa 2 CaCu 2 O 7-δ (Tl-1212) epitaxial films have been measured with x-ray photoelectron spectroscopy (XPS). The valence electronic structure has been determined using the full-potential linear muffin-tin-orbital band-structure method and measured with XPS. The calculations show that a van Hove singularity (VHS) lies above the Fermi level (E F ) for the stoichiometric compound (δ=0), while for 50% oxygen vacancies in the Tl-O layer (δ=0.5) E F is in close proximity to the VHS. Samples annealed in nitrogen (to reduce the hole overdoping by the removal of oxygen) exhibit higher core-level binding energies and a higher T c , consistent with a shift of E F closer to the VHS. Comparisons are made to the core levels and valence bands of Tl 2 Ba 2 CaCu 2 O 8+δ (Tl-2212) and HgBa 2 CaCu 2 O 6+δ (Hg-1212). The similarity of the Cu 2p 3/2 spectra for Tl-1212 and Tl-2212 indicates that the number of Tl-O layers has little effect on the Cu-O bonding. However, the Tl-1212 and Hg-1212 Cu 2p 3/2 signals exhibit differences which suggest that the replacement of Tl 3+ with Hg 2+ results in a decrease in the O 2p→Cu 3d charge-transfer energy and differences in the probabilities of planar vs apical oxygen charge transfer and/or Zhang-Rice singlet-state formation. Differences between the Tl-1212 and the Tl-2212 and Hg-1212 measured valence bands are consistent with the calculated Cu 3d and (Tl,Hg) 6s/5d partial densities of states. copyright 1997 The American Physical Society

  3. Electronic Structure of TlBa2CaCu2O(7-Delta)

    Science.gov (United States)

    Vasquez, R. P.; Novikov, D. L.; Freeman, A. J.; Siegal, M. P.

    1997-01-01

    The core levels of TlBa2CaCu2O(7-delta) (Tl-1212) epitaxial films have been measured with X-ray photoelectron spectroscopy (XPS). The valence electronic structure has been determined using the full-potential linear muffin-tin-orbital band-structure method and measured with XPS. The calculations show that a van Hove singularity (VHS) lies above the Fermi level (E(sub F)) for the stoichiometric compound (delta = 0.5), while for 50% oxygen vacancies in the Tl-O layer (delta = 0.5) E(sub F) is in close proximity to the VHS. Samples annealed in nitrogen (to reduce the hole overdoping by the removal of oxygen) exhibit higher core-level binding energies and a higher T(sub c), consistent with a shift of E(sub F) closer to the VHS. Comparisons are made to the core levels and valence bands of Tl2Ba2CaCu2O(8 + delta)(Tl-2212) and HgBa2CaCu2O)6 + delta) (Hg- 1212). The similarity of the Cu 2p(sub 3/2) spectra for Tl-1212 and Tl-2212 indicates that the number of Tl-O layers has little effect on the Cu-O bonding. However, the Tl-1212 and Hg-1212 Cu 2p(sub 3/2) signals exhibit differences which suggest that the replacement of T(sup 3+) with Hg(sup 2+) results in a decrease in the O 2p right arrow Cu 3d charge-transfer energy and differences in the probabilities of planar vs apical oxygen charge transfer and/or Zhang-Rice singlet-state formation. Differences between the Tl-1212 and the Tl-2212 and Hg-1212 measured valence bands are consistent with the calculated Cu 3d and (Tl,Hg) 6s/5d partial densities of states.

  4. Reaction mechanism of CO oxidation on Cu2O(111): A density functional study

    Science.gov (United States)

    Sun, Bao-Zhen; Chen, Wen-Kai; Xu, Yi-Jun

    2010-10-01

    The possible reaction mechanisms for CO oxidation on the perfect Cu2O(111) surface have been investigated by performing periodic density functional theoretical calculations. We find that Cu2O(111) is able to facilitate the CO oxidation with different mechanisms. Four possible mechanisms are explored (denoted as MER1, MER2, MLH1, and MLH2, respectively): MER1 is CO(gas)+O2(ads)-->CO2(gas) MER2 is CO(gas)+O2(ads)-->CO3(ads)-->O(ads)+CO2(gas) MLH1 refers to CO(ads)+O2(ads)-->O(ads)+CO2(ads) and MLH2 refers to CO(ads)+O2(ads)-->OOCO(ads)-->O(ads)+CO2(ads). Our transition state calculations clearly reveal that MER1 and MLH2 are both viable; but MER1 mechanism preferentially operates, in which only a moderate energy barrier (60.22 kJ/mol) needs to be overcome. When CO oxidation takes place along MER2 path, it is facile for CO3 formation, but is difficult for its decomposition, thereby CO3 species can stably exist on Cu2O(111). Of course, the reaction of CO with lattice O of Cu2O(111) is also considered. However, the calculated barrier is 600.00 kJ/mol, which is too large to make the path feasible. So, we believe that on Cu2O(111), CO reacts with adsorbed O, rather than lattice O, to form CO2. This is different from the usual Mars-van Krevene mechanism. The present results enrich our understanding of the catalytic oxidation of CO by copper-based and metal-oxide catalysts.

  5. Nonlinear optical and microscopic analysis of Cu2+ doped zinc thiourea chloride (ZTC) monocrystal

    Science.gov (United States)

    Ramteke, S. P.; Anis, Mohd; Pandian, M. S.; Kalainathan, S.; Baig, M. I.; Ramasamy, P.; Muley, G. G.

    2018-02-01

    Organometallic crystals offer considerable nonlinear response therefore, present article focuses on bulk growth and investigation of Cu2+ ion doped zinc thiourea chloride (ZTC) crystal to explore its technological impetus for laser assisted nonlinear optical (NLO) device applications. The Cu2+ ion doped ZTC bulk single crystal of dimension 03 × 2.4 × 0.4 cm3 has been grown from pH controlled aqueous solution by employing slow solvent evaporation technique. The structural analysis has been performed by means of single crystal X-ray diffraction technique. The doping of Cu2+ ion in ZTC crystal matrix has been confirmed by means of energy dispersive spectroscopic (EDS) technique. The origin of nonlinear optical properties in Cu2+ ion doped ZTC crystal has been studied by employing the Kurtz-Perry test and Z-scan analysis. The remarkable enhancement in second harmonic generation (SHG) efficiency of Cu2+ ion doped ZTC crystal with reference to ZTC crystal has been determined. The He-Ne laser assisted Z-scan analysis has been performed to determine the third order nonlinear optical (TONLO) nature of grown crystal. The TONLO parameters such as susceptibility, absorption coefficient, refractive index and figure of merit of Cu-ZTC crystal have been evaluated using the Z-scan transmittance data. The laser damage threshold of grown crystal to high intensity of Nd:YAG laser is found to be 706.2 MW/cm2. The hardness number, work hardening index, yield strength and elastic stiffness coefficient of grown crystal has been investigated under microhardness study. The etching study has been carried out to determine the growth likelihood, nature of etch pits and surface quality of grown crystal.

  6. Nitrogen-doped carbon decorated Cu2NiSnS4 microflowers as superior anode materials for long-life lithium-ion batteries

    Science.gov (United States)

    Pan, Pei; Chen, Lihui; Ding, Yu; Du, Jun; Feng, Chuanqi; Fu, Zhengbin; Qin, Caiqin; Wang, Feng

    2018-05-01

    Nitrogen-doped carbon (NC) decorated Cu2NiSnS4 (CNTS) microflower composites (NC@CNTS) were fabricated through a facile solvothermal and pyrrole polymerization with further annealing treatment. The NC@CNTS composites possessed a three-dimension (3D) microflower-like hierarchical structure. The unique microflower structure of NC@CNTS composites exhibited remarkable electrochemical performance as electrode materials for long life lithium ion batteries. The as-prepared composites had a stable and reversible capacity that reached 943 mA h g-1 after 160 cycles at a current rate of 0.1 A g-1. It showed satisfactory cycle stability and rate capability even at 2 A g-1, and specific capacity stabilized at 288 mA g-1 after 1000 cycles. The present facile and cost-effective strategy can be applied for the synthesis of other transition metal sulfide nanomaterials for energy storage and conversion applications.

  7. WORKSHOPS: Radiofrequency superconductivity

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    In the continual push towards higher energy particle beams, superconducting radiofrequency techniques now play a vital role, highlighted in the fifth workshop on radiofrequency superconductivity, held at DESY from 19 - 24 August 1991

  8. WORKSHOPS: Radiofrequency superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1992-01-15

    In the continual push towards higher energy particle beams, superconducting radiofrequency techniques now play a vital role, highlighted in the fifth workshop on radiofrequency superconductivity, held at DESY from 19 - 24 August 1991.

  9. N-type Cu2O Film for Photocatalytic and Photoelectrocatalytic Processes: Its stability and Inactivation of E. coli

    International Nuclear Information System (INIS)

    Xiong, Liangbin; Ng, Tsz Wai; Yu, Ying; Xia, Dehua; Yip, Ho Yin; Li, Guiying; An, Taicheng; Zhao, Huijun; Wong, Po Keung

    2015-01-01

    Highlights: • Photoelectrocatalytic inactivation of E. coli by Cu 2 O film was firstly reported. • 7 log of E. coli could be completely inactivated in 2 h by Cu 2 O with a 0.1 V bias. • Charge transfer between Cu 2 O and E. coli was monitored by electrochemical technique. • Inactivation of E. coli by electric charges of electrodes was in-depth investigated. • Stability of N-type Cu 2 O as a photocatalyst was studied for the first time. - ABSTRACT: Photoelectrocatalytic (PEC) inactivation of Escherichia coli K-12 by cuprous oxide (Cu 2 O) film irradiated by visible light is firstly reported. A complete inactivation of about 7 log of E. coli was obtained for Cu 2 O film within 6 h. The bacterial inactivation efficiency was significantly improved in a photoelectrochemical cell, in which 7 log of E. coli could be completely inactivated within 2 h by Cu 2 O film with a 0.1 V bias. Electric charge transfer between electrodes and E. coli, and electric charge inactivation towards E. coli were investigated using membrane-separated reactor combined with short circuit photocurrent technique. H 2 O 2 , hole, and toxicity of Cu 2 O film were found responsible for the inactivation of E. coli. Toxicity of copper ions (including Cu 2+ and Cu + ) leakage from Cu 2 O films was determined and the results showed that the amount of leakage copper ions was not toxic to E. coli. Finally, the Cu 2 O film was proved to be effective and reusable for PC and PEC inactivation of E. coli

  10. Superconducting pulsed magnets

    CERN Multimedia

    CERN. Geneva

    2006-01-01

    Lecture 1. Introduction to Superconducting Materials Type 1,2 and high temperature superconductors; their critical temperature, field & current density. Persistent screening currents and the critical state model. Lecture 2. Magnetization and AC Loss How screening currents cause irreversible magnetization and hysteresis loops. Field errors caused by screening currents. Flux jumping. The general formulation of ac loss in terms of magnetization. AC losses caused by screening currents. Lecture 3. Twisted Wires and Cables Filamentary composite wires and the losses caused by coupling currents between filaments, the need for twisting. Why we need cables and how the coupling currents in cables contribute more ac loss. Field errors caused by coupling currents. Lecture 4. AC Losses in Magnets, Cooling and Measurement Summary of all loss mechanisms and calculation of total losses in the magnet. The need for cooling to minimize temperature rise in a magnet. Measuring ac losses in wires and in magnets. Lecture 5. Stab...

  11. Study of surfaces and interfaces in CdS-Cu2S and (Cd sub(x) Zn sub(1-x))S-Cu2S solar cells

    International Nuclear Information System (INIS)

    Dhere, N.G.; Dhere, R.G.; Bloss, W.H.; Schock, H.W.; Bauer, E.; Cyris, P.

    1983-01-01

    Auger microprobe was used for the analysis of interfaces and surfaces in several stages involved in the preparation of solar cells, in order to study the origin of adhesion problems and to study the formation of CdS-Cu 2 S barrier by the wet method. The detachment of the first CdS and (Cd sub(x) Zn sub(1-x))S films, during the dip process, was attributed to the contamination of Cr-Ag metallic substrates by existing chlorine from the environment next to the sea, due to long film stocking, by degasified species from the evaporating material and by the ejection of particles together with CdS vapour during deposition. The formation of conical mounds on the surface and of the CdS-Cu 2 S barrier at aproximatelly 3000 A depth in the dipped samples were observed. The migration of copper towards surface direction and the formation of a superficial thin layer of copper oxide after treatment in H 2 plasma and air heating, were also verified. (C.L.B.) [pt

  12. Computational insight on the structural, mechanical and thermal properties of Cu2CdSnSe4 and Cu2HgSnSe4 adamantine materials

    Directory of Open Access Journals (Sweden)

    S. Bensalem

    2016-12-01

    Full Text Available Through first-principles calculation based on the density functional theory (DFT within the pseudo potential-plane wave (PP-PW approach, we studied the structural, mechanical and thermal properties of Cu2CdSnSe4 and Cu2HgSnSe4 adamantine materials. The calculated lattice parameters are in good agreement with experimental and theoretical reported data. The elastic constants are calculated for both compounds using the static finite strain scheme. The hydrostatic pressure action on the elastic constants predicts that both materials are mechanically stable up to 10 GPa. The polycrystalline mechanical parameters, i.e., the anisotropy factor (A, bulk modulus (B, shear modulus (G, Young's modulus (E, Lame's coefficient (λ and Poisson's ratio (ν have been estimated from the calculated single crystal elastic constants. The analysis of B/G ratio shows that the two studied compounds behave as ductile. Based on the calculated mechanical parameters, the Debye temperature and the thermal conductivity have been probed. In the framework of the quasi-harmonic approximation, the temperature dependence of the lattice heat capacity of both crystals has been investigated.

  13. Mechanism of a strong rise of Tc due to the calcium doping in Y1-xCaxBa2Cu2.8Zn0.2Oy

    International Nuclear Information System (INIS)

    Martynova, O.A.; Potapov, D.V.; Gasumyants, V.E.; Vladimirskaya, E.V.

    2011-01-01

    Highlights: → Calcium is observed to restore superconductivity in Y 1-x Ca x Ba 2 Cu 2.8 Zn 0.2 O y . → Parameters of the band spectrum and charge-carrier system are determined. → The calcium doping is shown to give a noticeable contribution to the DOS function. → The mechanism of calcium effect on T c in doped YBa 2 Cu 3 O y is discussed. - Abstract: The normal-state transport properties and the critical temperature, T c , for three series of Y 1-x Ca x Ba 2 Cu 2.8 Zn 0.2 O y (x = 0-0.2) samples with different oxygen content have been investigated and discussed in comparison with results for other calcium-doped YBa 2 Cu 3 O y . We have observed the calcium doping to restore the superconductivity in the YBa 2 Cu 3 O y system even in case of the preliminary T c suppression by the direct destruction of the CuO 2 planes due to a preliminary doping by zinc. The T c value rises strongly with increasing calcium content and this rise becomes faster for the oxygen-reduced series. Based on a narrow-band model, the parameters of the band spectrum structure and the charge-carrier system in the normal state were determined from the analysis of the thermopower temperature dependences in order to reveal the mechanism of the T c rise under the Ca influence. It is shown that the T c increase in Y 1-x Ca x Ba 2 Cu 2.8 Zn 0.2 O y is related to the direct Ca ions effect. The mechanism of the calcium influence on the T c value is discussed with respect to the Ca-induced conduction band modification. The calcium doping in Y 1-x Ca x Ba 2 Cu 2.8 Zn 0.2 O y is shown to give a noticeable contribution to the density-of-states function leading to a strong rise in its value at the Fermi level that results in a restoration of the superconducting properties.

  14. Combinatorial development of Cu2SnS3 as an earth abundant photovoltaic absorber

    Science.gov (United States)

    Baranowski, Lauryn L.

    The development of high efficiency, earth abundant photovoltaic absorbers is critical if photovoltaics are to be implemented on the TW scale. Although traditional thin films absorbers such as Cu(In,Ga)Se2 and CdTe have achieved over 20% device efficiencies, the ultimately scalability of these devices may be limited by elemental scarcity and toxicity issues. To date, the most successful earth abundant thin film absorber is Cu2ZnSn(S,Se) 4, which has achieved 12.6% efficiency as of 2014. However, chemical complexity and disorder issues with this material have made the path to higher efficiency CZTSSe devices unclear. As a result, many researchers are now exploring alternative earth abundant absorber materials. In this thesis, we apply our "rapid development" methodology to the exploration of alternative photovoltaic absorbers. The rapid development (RD) methodology, consisting of exploration, research, and development stages, uses complementary theory and experiment to assess candidate materials and down-select in each stage. The overall result is that, in the time span of ~2-3 years, we are able to rapidly go from tens of possible absorber materials to 1-2 working PV device prototypes. Here, we demonstrate the RD approach as applied to the Cu-Sn-S system. We begin our investigation of the Cu-Sn-S system by evaluating the thermodynamic stability, electrical transport, electronic structure, and optical and defect properties of candidate materials using complementary theory and experiment. We find that Cu2SnS3 is the most promising absorber candidate because of its strong optical absorption, tunable doping, and wide stability range. Our other candidate compounds suffer from serious flaws that preclude them from being successful photovoltaic absorbers, including too high experimental conductivity (Cu4SnS4), or poor hole transport and low absorption coefficient (Cu4Sn7S16). Next, we investigate the doping and defect physics of Cu2SnS 3. We identify the origins of the

  15. Superconducting current in a bisoliton superconductivity model

    International Nuclear Information System (INIS)

    Ermakov, V.N.; Kruchinin, S.P.; Ponezha, E.A.

    1991-01-01

    It is shown that the transition into a superconducting state with the current which is described by a bisoliton superconductivity model is accompanied by the deformation of the spectrum of one-particle states of the current carriers. The deformation value is proportional to the conducting current force. The residuaby resistance in such state is absent

  16. First-principles study of defect formation in a photovoltaic semiconductor Cu2ZnGeSe4

    Science.gov (United States)

    Nishihara, Hironori; Maeda, Tsuyoshi; Wada, Takahiro

    2018-02-01

    The formation energies of neutral Cu, Zn, Ge, and Se vacancies in kesterite-type Cu2ZnGeSe4 were evaluated by first-principles pseudopotential calculations using plane-wave basis functions. The calculations were performed at typical points in Cu-(Zn1/2Ge1/2)-Se and Cu3Se2-ZnSe-GeSe2 pseudoternary phase diagrams for Cu2ZnGeSe4. The results were compared with those for Cu2ZnSnSe4, Cu2ZnGeS4, and Cu2ZnSnS4 calculated using the same version of the CASTEP program code. The results indicate that Cu vacancies are easily formed in Cu2ZnGeSe4 under the Cu-poor condition as in the above compounds and CuInSe2, suggesting that Cu2ZnGeSe4 is also a preferable p-type absorber material for thin-film solar cells. The formation energies of possible antisite defects, such as CuZn and CuGe, and of possible complex defects, such as CuZn+ZnCu, were also calculated and compared within the above materials. The antisite defect of CuZn, which has the smallest formation energy within the possible defects, is concluded to be the most hardly formed in Cu2ZnGeSe4 among the compounds.

  17. Abstracts of The First Polish-US Conference on High Temperature Superconductivity

    International Nuclear Information System (INIS)

    1995-01-01

    The current problems in high temperature superconductivity science have been presented at the conference. The two main topics have been mostly represented: superconducting material research and fundamental physical research on superconductivity mechanisms. Superconducting material preparation, chemical composition, magnetic and electrical properties of different type of high temperature superconductors, material structure and its influence on superconducting properties and related problems were included in the first of the general topics. In the range of second general topic of the two listed above, many theoretical models being applied for explanation of superconductivity mechanism in different systems up and below transition temperature were presented

  18. Sensitive and selective detection of Hg2+ and Cu2+ ions by fluorescent Ag nanoclusters synthesized via a hydrothermal method

    Science.gov (United States)

    Liu, Jing; Ren, Xiangling; Meng, Xianwei; Fang, Zheng; Tang, Fangqiong

    2013-09-01

    An easily prepared fluorescent Ag nanoclusters (Ag NCs) probe for the sensitive and selective detection of Hg2+ and Cu2+ ions was developed here. The Ag NCs were synthesized by using polymethacrylic acid sodium salt as a template via a convenient hydrothermal process. The as-prepared fluorescent Ag NCs were monodispersed, uniform and less than 2 nm in diameter, and can be quenched in the presence of mercury (Hg2+) or copper (Cu2+) ions. Excellent linear relationships existed between the quenching degree of the Ag NCs and the concentrations of Hg2+ or Cu2+ ions in the range of 10 nM to 20 μM or 10 nM to 30 μM, respectively. By using ethylenediaminetetraacetate (EDTA) as the masking agent of Cu2+, Hg2+ was exclusively detected in coexistence with Cu2+ with high sensitivity (LOD = 10 nM), which also provided a reusable detection method for Cu2+. Furthermore, the different quenching phenomena caused by the two metals ions such as changes in visible colour, shifts of UV absorbance peaks and changes in size of Ag NCs make it easy to distinguish between them. Therefore the easily synthesized fluorescent Ag NCs may have great potential as Hg2+ and Cu2+ ions sensors.An easily prepared fluorescent Ag nanoclusters (Ag NCs) probe for the sensitive and selective detection of Hg2+ and Cu2+ ions was developed here. The Ag NCs were synthesized by using polymethacrylic acid sodium salt as a template via a convenient hydrothermal process. The as-prepared fluorescent Ag NCs were monodispersed, uniform and less than 2 nm in diameter, and can be quenched in the presence of mercury (Hg2+) or copper (Cu2+) ions. Excellent linear relationships existed between the quenching degree of the Ag NCs and the concentrations of Hg2+ or Cu2+ ions in the range of 10 nM to 20 μM or 10 nM to 30 μM, respectively. By using ethylenediaminetetraacetate (EDTA) as the masking agent of Cu2+, Hg2+ was exclusively detected in coexistence with Cu2+ with high sensitivity (LOD = 10 nM), which also provided a

  19. Superconducting energy storage magnet

    Science.gov (United States)

    Boom, Roger W. (Inventor); Eyssa, Yehia M. (Inventor); Abdelsalam, Mostafa K. (Inventor); Huang, Xianrui (Inventor)

    1993-01-01

    A superconducting magnet is formed having composite conductors arrayed in coils having turns which lie on a surface defining substantially a frustum of a cone. The conical angle with respect to the central axis is preferably selected such that the magnetic pressure on the coil at the widest portion of the cone is substantially zero. The magnet structure is adapted for use as an energy storage magnet mounted in an earthen trench or tunnel where the strength the surrounding soil is lower at the top of the trench or tunnel than at the bottom. The composite conductor may be formed having a ripple shape to minimize stresses during charge up and discharge and has a shape for each ripple selected such that the conductor undergoes a minimum amount of bending during the charge and discharge cycle. By minimizing bending, the working of the normal conductor in the composite conductor is minimized, thereby reducing the increase in resistance of the normal conductor that occurs over time as the conductor undergoes bending during numerous charge and discharge cycles.

  20. Effect of Zn/Sn molar ratio on the microstructural and optical properties of Cu2Zn1-xSnxS4 thin films prepared by spray pyrolysis technique

    Science.gov (United States)

    Thiruvenkadam, S.; Prabhakaran, S.; Sujay Chakravarty; Ganesan, V.; Vasant Sathe; Santhosh Kumar, M. C.; Leo Rajesh, A.

    2018-03-01

    Quaternary kesterite Cu2ZnSnS4 (CZTS) compound is one of the most promising semiconductor materials consisting of abundant and eco-friendly elements for absorption layer in thin film solar cells. The effect of Zn/Sn ratio on Cu2Zn1-xSnxS4 (0 ≤ x ≤ 1) thin films were studied by deposited by varying molar volumes in the precursor solution of zinc and tin was carried out in proportion of (1-x) and x respectively onto soda lime glass substrates kept at 573 K by using chemical spray pyrolysis technique. The GIXRD pattern revealed that the films having composites of Cu2ZnSnS4, Cu2SnS3, Sn2S3, CuS and ZnS phases. The crystallinity and grain size were found to increase by increasing the x value and the preferential orientation along (103), (112), (108) and (111) direction corresponding to CZTS, Cu2SnS3, CuS, and ZnS phases respectively. Micro-Raman spectra exposed a prominent peak at 332 cm-1 corresponding to the CZTS phase. Atomic force microscopy was employed to study the grain size and roughness of the deposited thin films. The optical band gap was found to lie between 1.45 and 2.25 eV and average optical absorption coefficient was found to be greater than 105 cm-1. Hall measurements exhibited that all the deposited Cu2Zn1-xSnxS4 films were p type and the resistivity lies between 10.9 ×10-2Ωcm and 149.6 × 10-2Ωcm .

  1. A study on the development of high-Tc superconducting wire

    International Nuclear Information System (INIS)

    Won, Dong Yeon; Chang, In Soon; Lee, Jong Min; Um, Tae Yoon; Hong, Kyae Won; Lee, Ho Jin; Lee, Hee Kwun; Kim, Chan Joong; Park, Soon Dong; Kim, Woo Gon; Kim, Ki Baek; Kwon, Sun Chil

    1992-10-01

    On this study Y-Ba-Cu-O was prepared by partial melt process and superconducting wire was fabricated by powder-in-tube method. First, mechancial properties, electrical properties, microstructure and oxygen diffusion behavior were observed. Second, through fabricated superconducting wire, conceptual design, composition and plasticity of filament superconducting wire were investigated. (Author)

  2. Doping dependent room-temperature ferromagnetism and structural properties of dilute magnetic semiconductor ZnO:Cu2+ nanorods

    International Nuclear Information System (INIS)

    Sharma, Prashant K.; Dutta, Ranu K.; Pandey, Avinash C.

    2009-01-01

    Copper doped ZnO nanoparticles were synthesized by the chemical technique based on the hydrothermal method. The crystallite structure, morphology and size were determined by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) for different doping percentages of Cu 2+ (1-10%). TEM/SEM images showed formation of uniform nanorods, the aspect ratio of which varied with doping percentage of Cu 2+ . The wurtzite structure of ZnO gradually degrades with the increasing Cu 2+ doping concentration and an additional CuO associated diffraction peak was observed above 8% of Cu 2+ doping. The change in magnetic behavior of the nanoparticles of ZnO with varying Cu 2+ doping concentrations was investigated using a vibrating sample magnetometer (VSM). Initially these nanoparticles showed strong room-temperature ferromagnetic behavior, however at higher doping percentage of copper the ferromagnetic behavior was suppressed and paramagnetic nature was enhanced.

  3. Study of Cu2O\\ZnO nanowires heterojunction designed by combining electrodeposition and atomic layer deposition

    Science.gov (United States)

    Makhlouf, Houssin; Weber, Matthieu; Messaoudi, Olfa; Tingry, Sophie; Moret, Matthieu; Briot, Olivier; Chtoutou, Radhouane; Bechelany, Mikhael

    2017-12-01

    Cu2O/ZnO nanowires (NWs) heterojunctions were successfully prepared by combining Atomic layer Deposition (ALD) and Electrochemical Deposition (ECD) processes. The crystallinity, morphology and photoconductivity properties of the Cu2O/ZnO nanostructures have been investigated. The properties of the Cu2O absorber layer and the nanostructured heterojunction were studied in order to understand the mechanisms lying behind the low photoconductivity measured. It has been found that the interface state defects and the high resistivity of Cu2O film were limiting the photovoltaic properties of the prepared devices. The understanding presented in this work is expected to enable the optimization of solar cell devices based on Cu2O/ZnO nanomaterials and improve their overall performance.

  4. Enhanced superconductivity of fullerenes

    Energy Technology Data Exchange (ETDEWEB)

    Washington, II, Aaron L.; Teprovich, Joseph A.; Zidan, Ragaiy

    2017-06-20

    Methods for enhancing characteristics of superconductive fullerenes and devices incorporating the fullerenes are disclosed. Enhancements can include increase in the critical transition temperature at a constant magnetic field; the existence of a superconducting hysteresis over a changing magnetic field; a decrease in the stabilizing magnetic field required for the onset of superconductivity; and/or an increase in the stability of superconductivity over a large magnetic field. The enhancements can be brought about by transmitting electromagnetic radiation to the superconductive fullerene such that the electromagnetic radiation impinges on the fullerene with an energy that is greater than the band gap of the fullerene.

  5. Superconductivity in Medicine

    Science.gov (United States)

    Alonso, Jose R.; Antaya, Timothy A.

    2012-01-01

    Superconductivity is playing an increasingly important role in advanced medical technologies. Compact superconducting cyclotrons are emerging as powerful tools for external beam therapy with protons and carbon ions, and offer advantages of cost and size reduction in isotope production as well. Superconducting magnets in isocentric gantries reduce their size and weight to practical proportions. In diagnostic imaging, superconducting magnets have been crucial for the successful clinical implementation of magnetic resonance imaging. This article introduces each of those areas and describes the role which superconductivity is playing in them.

  6. Visible light responsive Cu2MoS4 nanosheets incorporated reduced graphene oxide for efficient degradation of organic pollutant

    Science.gov (United States)

    Rameshbabu, R.; Vinoth, R.; Navaneethan, M.; Harish, S.; Hayakawa, Y.; Neppolian, B.

    2017-10-01

    Visible light active copper molybdenum sulfide (Cu2MoS4) nanosheets were successfully anchored on reduced graphene oxide (rGO) using facile hydrothermal method. During the hydrothermal reaction, reduction of graphene oxide into rGO and the formation of Cu2MoS4 nanosheets were successfully obtained. The charge transfer interaction between the rGO sheets and Cu2MoS4 nanosheets extended the absorption to visible region in comparison with bare Cu2MoS4 nanosheets i.e without rGO sheets. Furthermore, the notable photoluminescence quenching observed for Cu2MoS4/rGO nanocomposite revealed the effective role of rGO towards the significant inhibition of electron-hole pair recombination. The photocatalytic efficiencies of bare Cu2MoS4 and Cu2MoS4/rGO nanocomposite was evaluated for the degradation of methyl orange dye under visible irradiation (λ > 420 nm). A maximum photodegradation efficiency of 99% was achieved for Cu2MoS4/rGO nanocomposite, while only 64% photodegradation was noted for bare Cu2MoS4. The enhanced optical absorption in visible region, high surface area, and low charge carrier recombination in the presence of rGO sheets were the main reasons for the enhancement in photodegardation of MO dye. In addition, the resultant Cu2MoS4/rGO nanocomposite was found to be reusable for five successive cycles without significant loss in its photocatalytic performance.

  7. Abrupt onset of a second energy gap at the superconducting transition of underdoped Bi2212

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Zahid; Lee, W.S.; Vishik, I.M.; Tanaka, K.; Lu, D.H.; Sasagawa, T.; Nagaosa, N.; Devereaux, T.P.; Hussain, Z.; Shen, Z.-X.

    2007-05-26

    he superconducting gap--an energy scale tied to the superconducting phenomena--opens on the Fermi surface at the superconducting transition temperature (Tc) in conventional BCS superconductors. In underdoped high-Tc superconducting copper oxides, a pseudogap (whose relation to the superconducting gap remains a mystery) develops well above Tc (refs 1, 2). Whether the pseudogap is a distinct phenomenon or the incoherent continuation of the superconducting gap above Tc is one of the central questions in high-Tc research3, 4, 5, 6, 7, 8. Although some experimental evidence suggests that the two gaps are distinct9, 10, 11, 12, 13, 14, 15, 16, 17, 18, this issue is still under intense debate. A crucial piece of evidence to firmly establish this two-gap picture is still missing: a direct and unambiguous observation of a single-particle gap tied to the superconducting transition as function of temperature. Here we report the discovery of such an energy gap in underdoped Bi2Sr2CaCu2O8+delta in the momentum space region overlooked in previous measurements. Near the diagonal of Cu?O bond direction (nodal direction), we found a gap that opens at Tc and has a canonical (BCS-like) temperature dependence accompanied by the appearance of the so-called Bogoliubov quasi-particles, a classical signature of superconductivity. This is in sharp contrast to the pseudogap near the Cu?O bond direction (antinodal region) measured in earlier experiments19, 20, 21.

  8. Spectroscopic ellipsometry study of Cu2ZnSnS4 bulk poly-crystals

    Science.gov (United States)

    Levcenko, S.; Hajdeu-Chicarosh, E.; Garcia-Llamas, E.; Caballero, R.; Serna, R.; Bodnar, I. V.; Victorov, I. A.; Guc, M.; Merino, J. M.; Pérez-Rodriguez, A.; Arushanov, E.; León, M.

    2018-04-01

    The linear optical properties of Cu2ZnSnS4 bulk poly-crystals have been investigated using spectroscopic ellipsometry in the range of 1.2-4.6 eV at room temperature. The characteristic features identified in the optical spectra are explained by using the Adachi analytical model for the interband transitions at the corresponding critical points in the Brillouin zone. The experimental data have been modeled over the entire spectral range taking into account the lowest E0 transition near the fundamental absorption edge and E1A and E1B higher energy interband transitions. In addition, the spectral dependences of the refractive index, extinction coefficient, absorption coefficient, and normal-incidence reflectivity values have been accurately determined and are provided since they are essential data for the design of Cu2ZnSnS4 based optoelectronic devices.

  9. What is the band alignment of Cu2ZnSn(S,Se)4 solar cells?

    DEFF Research Database (Denmark)

    Crovetto, Andrea; Hansen, Ole

    2017-01-01

    The band alignment at the Cu2ZnSn(S,Se)4/CdS solar cell heterojunction is a controversial issue, as different measurements and calculations point to substantially different conduction band offsets (CBO). As the actual value of the CBO has profound implications on solar cell performance, the aim...... of this work is to separate genuine process-dependent variations in the CBO from errors in its experimental determination. We argue that the two most likely mechanisms responsible for real CBO variations are Fermi level pinning (which tends to decrease the CBO) and chemical interdiffusion (which tends...... measurement approaches. Interestingly, a rough correlation can be established between the CBO measured at the Cu2ZnSnS4/CdS interface by different groups and their corresponding solar cell efficiency: lower-efficiency cells often have a large "cliff-like" offset, whereas most high-efficiency cells have...

  10. Doping dependence of low-energy quasiparticle excitations in superconducting Bi2212.

    Science.gov (United States)

    Ino, Akihiro; Anzai, Hiroaki; Arita, Masashi; Namatame, Hirofumi; Taniguchi, Masaki; Ishikado, Motoyuki; Fujita, Kazuhiro; Ishida, Shigeyuki; Uchida, Shinichi

    2013-12-05

    : The doping-dependent evolution of the d-wave superconducting state is studied from the perspective of the angle-resolved photoemission spectra of a high-Tc cuprate, Bi2Sr2CaCu2 O8+δ (Bi2212). The anisotropic evolution of the energy gap for Bogoliubov quasiparticles is parametrized by critical temperature and superfluid density. The renormalization of nodal quasiparticles is evaluated in terms of mass enhancement spectra. These quantities shed light on the strong coupling nature of electron pairing and the impact of forward elastic or inelastic scatterings. We suggest that the quasiparticle excitations in the superconducting cuprates are profoundly affected by doping-dependent screening.

  11. A manufacturing process for a mixed-oxide type superconducting material

    International Nuclear Information System (INIS)

    Gendre, P.; Regnier, P.; Schmirgeld-Mignot, L.; Marquet, A.

    1995-01-01

    In order to produce high temperature superconducting materials such as YBaCuO and Bi 2 Sr 2 Ca Cu 2 O 8 , a process is presented which consists in an electrodeposition on a conductive substrate of successive layers made of the metallic elements composing the superconductor, with only one element in each layer; between each layer deposition, an intermediary oxide-reaction thermal treatment is carried out; a global oxidation thermal treatment is then finally conducted to produce the mixed oxide material. Narrow superconducting transitions and high critical current densities are possible. 3 refs., 4 figs

  12. Superconductivity in transition metals.

    Science.gov (United States)

    Slocombe, Daniel R; Kuznetsov, Vladimir L; Grochala, Wojciech; Williams, Robert J P; Edwards, Peter P

    2015-03-13

    A qualitative account of the occurrence and magnitude of superconductivity in the transition metals is presented, with a primary emphasis on elements of the first row. Correlations of the important parameters of the Bardeen-Cooper-Schrieffer theory of superconductivity are highlighted with respect to the number of d-shell electrons per atom of the transition elements. The relation between the systematics of superconductivity in the transition metals and the periodic table high-lights the importance of short-range or chemical bonding on the remarkable natural phenomenon of superconductivity in the chemical elements. A relationship between superconductivity and lattice instability appears naturally as a balance and competition between localized covalent bonding and so-called broken covalency, which favours d-electron delocalization and superconductivity. In this manner, the systematics of superconductivity and various other physical properties of the transition elements are related and unified. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  13. Prediction of Chevrel superconducting phases

    International Nuclear Information System (INIS)

    Savitskij, E.M.; Kiseleva, N.N.

    1978-01-01

    Made is an attempt of predicting the possibility of formation of compounds of Mo 3 Se 4 type structure having critical temperatures of transition into superconducting state more than 4.2 K. Cybernetic method of teaching an electronic computer to form notions is used for prediction. Prediction system constructs logic dependence of forming Chevrel superconducting phase of the Asub(x)Bsub(6)Ssub(8) composition (A being an element of the periodic system; B=Cr, Mo, W, Re) and Asub(x)Bsub(6)Ssub(8) compounds having a critical temperature of more than 4.2 K on the properties of A and B elements. A conclusion is made that W, Re, Cr do not form Chevrel phases of the Asub(x)Bsub(6)Ssub(8) composition as B component. Be, Hg, Ra, B, Ac are the reserve for obtaining Asub(x)Mosub(6)Ssub(8) phases. Agsub(x)Mosub(6)Ssub(8) compound may have a high critical temperature. The ways of a critical temperature increase for Chevrel phases are connected with the search of optimal technological conditions for already known superconducting compounds and also with introduction of impurities fixing a distance between sulfur cubes

  14. Extraordinary superconductor with nearly trivalent cerium, CeCu2Si2

    International Nuclear Information System (INIS)

    Ishikawa, M.; Jaccard, D.; Jorda, J.-L.

    1982-01-01

    Concentrating on the ternary phase diagram, the authors have performed a complementary investigation on CeCu 2 Si 2 and confirm that the compound containing nearly trivalent cerium ions is a new type of superconductor with Tsub(c) around 0.5 K. The analyses of the upper critical field curve support the description of the compound by heavy fermion quasiparticles. Other particular features of this compound are also presented. (Auth.)

  15. Ordered Phases in Cu2NiZn: A First-Principles Monte Carlo Study

    DEFF Research Database (Denmark)

    Simak, S.I.; Ruban, Andrei; Abrikosov, I.A.

    1998-01-01

    Monte Carlo simulations based on effective interactions obtained from first-principles calculations reveal the existence of three ordered phases in ternary Cu2NiZn: (i) "modified"-L1(0) (0-600 K), (ii) L1(2) (600-850 K), and (iii) L1(0) (850-1200 K). This is in contrast to the generally accepted...

  16. Electrodeposition mechanism of quaternary compounds Cu2ZnSnS4: Effect of the additives

    Science.gov (United States)

    Tang, Aiyue; Li, Zhilin; Wang, Feng; Dou, Meiling; Liu, Jingjun; Ji, Jing; Song, Ye

    2018-01-01

    The electrodeposition mechanism of pure phase Cu2ZnSnS4 (CZTS) thin film with subsequent annealing was investigated in detail. An electrolyte design principle of quaternary compounds was proposed. The complex ions of Cu(H2C6H5O7)+, Cu2(C6H5O7)+, Zn(C4H5O6)+, Sn(H2C6H5O7)+ and Sn2(C6H5O7)+, which influenced the reduction process and played important roles in co-deposition, were identified by UV spectra. Electrochemical studies indicated that trisodium citrate and tartaric acid could narrow the co-deposition potential range of the four elements to -0.8 V to -1.2 V (vs. SCE). The cause was the synergetic effect that trisodium citrate inhibited the reduction of Cu2+ and Sn2+ and tartaric acid promoted the reduction of Zn2+. The reduction of S2O32- was mainly attributed to the induction effect of the metallic ions, and the H+ dissociated from tartaric acid could also promote the cathode process of S2O32-. The reaction mechanism could be summarized as the following steps: (I) Cu(H2C6H5O7)+, Cu2(C6H5O7)+ → Cu, Sn(H2C6H5O7)+, Sn2(C6H5O7)+ → Sn, Zn(C4H5O6)+ → Zn; (II) the desorption of (H2C6H5O7)- and (C6H5O7)-, and the reduction of S2O32- induced by metallic ions and H+. The mechanism studies provided a path of electrolyte design for multicomponent compounds.

  17. Electronic structure of single crystalline Bi2(Sr,Ca,La)3Cu2O8

    International Nuclear Information System (INIS)

    Lindberg, P.A.P.; Shen, Z.X.; Dessau, D.S.; Wells, B.O.; Borg, A.; Mitzi, D.B.; Lindau, I.; Spicer, W.E.; Kapitulnik, A.

    1989-01-01

    Angle-resolved photoemission experiments on single crystals of Bi 2 (Sr,Ca,La) 3 Cu 2 O 8 are reported. The data show a dispersionless behavior of the valence band states as a function of the perpendicular component of the wave vector (along the c-axis), while as a function of the parallel component (in the a-b plane) clear dispersion occurs. Furthermore, polarization-dependent excitations reveal information on the symmetry of the unoccupied states

  18. Inkjet?Printed Cu2ZnSn(S, Se)4 Solar Cells

    OpenAIRE

    Lin, Xianzhong; Kavalakkatt, Jaison; Lux?Steiner, Martha Ch.; Ennaoui, Ahmed

    2015-01-01

    Cu2ZnSn(S, Se)4?based solar cells with total area (0.5 cm2) power conversion efficiency of 6.4% are demonstrated from thin film absorbers processed by inkjet printing technology of Cu?Zn?Sn?S precursor ink followed by selenization. The device performance is limited by the low fill factor, which is due to the high series resistance.

  19. Inkjet-Printed Cu2ZnSn(S, Se)4 Solar Cells.

    Science.gov (United States)

    Lin, Xianzhong; Kavalakkatt, Jaison; Lux-Steiner, Martha Ch; Ennaoui, Ahmed

    2015-06-01

    Cu 2 ZnSn(S, Se) 4 -based solar cells with total area (0.5 cm 2 ) power conversion efficiency of 6.4% are demonstrated from thin film absorbers processed by inkjet printing technology of Cu-Zn-Sn-S precursor ink followed by selenization. The device performance is limited by the low fill factor, which is due to the high series resistance.

  20. Coordination variation of hydrated Cu2+/Br1− ions traversing the interfacial water in mesopores

    Directory of Open Access Journals (Sweden)

    Q. Wang

    2012-06-01

    Full Text Available Resolution of the atomistic and electronic details about the coordination structure variation of hydrated ions in the interfacial water is still a tough challenge, which is, however, essentially important for the understanding of ion adsorption, permeation and other similar processes in aqueous solutions. Here we report the tracing of coordination structure variation for hydrated Cu2+/Br1- ions traversing the interfacial water in Vycor mesopores (ϕ = 7.6 nm by employing both X-ray absorption near edge structure and extended X-ray absorption fine structure spectroscopies. By controlled desorption/adsorption of water, the filling fraction of the mesopores, thus the water layer thickness, can be adjusted, which in turn effects the variation of coordination structure of the ions therein. It is found that both Cu2+ and Br1- ions prefer staying exclusively in the core water, and in this circumstance no ion pairs have been detected in the solution of concentrations up to 1.0 M. Following capillary decondensation occurring at a filling fraction of ∼35% which corresponds to a water layer of about three monolayers, Br1- ions begin immediately to reconstruct their first coordination shell, characterized by ionic dehydration, shrinkage of ion-water bond length, and formation of ion pairs. In contrast, Cu2+ ions can retain a bulk-like coordination structure till being driven to bond directly to the pore surface when the filling fraction is below 20%. At the final stage of dehydration via thermal vacuum treatment at 110°C, Cu2+ ions can be completely reduced to the Cu1+ state, and recover at room temperature only when the filling fraction is above 14%. These results may be inspirable for the investigation of similar problems concerning hydrated ions in water solution under different confining conditions.